• The (directed) links of the graph represent probabilistically weighted transitions between state-sets Specifically, the weight of the link from B to A should be defined as where P (o(S, A, t(T ))|o(S, B, T )) o(S, A, T ) denotes the presence of the system S in the state-set A during time-distribution T , and t() is a temporal succession function defined so that t(T ) refers to a time-distribution conceived as "after" T . A time-distribution is a probability distribution over time-points. The interaction of fuzziness and probability here is fairly straightforward and may be handled in the manner of PLN, as outlined in subsequent chapters. Note that the definition of link weights is dependent on the specific implementation of the temporal succession function, which includes an implicit time-scale. Suppose one has a transition graph corresponding to an environment; then a goal relative to that environment may be defined as a particular node in the transition graph. The goals of a particular system acting in that environment may then be conceived as one or more nodes in the transition graph. The system’s situation in the environment at any point in time may also be associated with one or more nodes in the transition graph; then, the system’s movement toward goal-achievement may be associated with paths through the environment’s transition graph leading from its current state to goal states. It may be useful for some purposes to filter the uncertain transition graph into a crisp transition graph by placing a threshold on the link weights, and removing links with weights below the threshold. The next concept to introduce is the world-mind transfer function, which maps world (environment) state-sets into organism (e.g. AI system) state-sets in a specific way. Given a world state-set W , the world-mind transfer function M maps W into various organism state-sets with various probabilities, so that we may say: M(W ) is the probability distribution of state-sets the organism tends to be in, when its environment is in state-set W . (Recall also that state-sets are fuzzy.) Now one may look at the spaces of world-paths and mind-paths. A world-path is a path through the world’s transition graph, and a mind-path is a path through the organism’s transi- 180 10 A Mind-World Correspondence Principle tion graph. Given two world-paths P and Q, it’s obvious how to define the composition P ∗Q one follows P and then, after that, follows Q, thus obtaining a longer path. Similarly for mind-paths. In category theory terms, we are constructing the free category associated with the graph: the objects of the category are the nodes, and the morphisms of the category are the paths. And category theory is the right way to be thinking here we want to be thinking about the relationship between the world category and the mind category. The world-mind transfer function can be interpreted as a mapping from paths to subgraphs: Given a world-path, it produces a set of mind state-sets, which have a number of links between them. One can then define a world-mind path transfer function M(P ) via taking the mind-graph M(nodes(P )), and looking at the highest-weight path spanning M(nodes(P )). (Here nodes? obviously means the set of nodes of the path P .) A functor F between the world category and the mind category is a mapping that preserves object identities and so that F (P ∗ Q) = F (P ) ∗ F (Q) We may also introduce the notion of an approximate functor, meaning a mapping F so that the average of d(F (P ∗ Q), F (P ) ∗ F (Q)) is small. One can introduce a prior distribution into the average here. This could be the Levin universal distribution or some variant (the Levin distribution assigns higher probability to computationally simpler entities). Or it could be something more purpose specific: for example, one can give a higher weight to paths leading toward a certain set of nodes (e.g. goal nodes). Or one can use a distribution that weights based on a combination of simplicity and directedness toward a certain set of nodes. The latter seems most interesting, and I will define a goal-weighted approximate functor as an approximate functor, defined with averaging relative to a distribution that balances simplicity with directedness toward a certain set of goal nodes. The move to approximate functors is simple conceptually, but mathematically it’s a fairly big step, because it requires us to introduce a geometric structure on our categories. But there are plenty of natural metrics defined on paths in graphs (weighted or not), so there’s no real problem here. 10.4 The Mind-World Correspondence Principle Now we finally have the formalism set up to make a non-trivial statement about the relationship between minds and worlds. Namely, the hypothesis that: MIND-WORLD CORRESPONDENCE PRINCIPLE For an organism with a reasonably high level of intelligence in a certain world, relative to a certain set of goals, the mind-world path transfer function is a goal-weighted approximate functor. 10.5 How Might the Mind-World Correspondence Principle Be Useful? 181 That is, a little more loosely: the hypothesis is that, for intelligence to occur, there has to be a natural correspondence between the transition-sequences of world-states and the corresponding transition-sequences of mind-states, at least in the cases of transition-sequences leading to relevant goals. We suspect that a variant of the above proposition can be formally proved, using the definition of general intelligence presented in Chapter 7. The proof of a theorem corresponding to the above would certainly constitute an interesting start toward a general formal theory of general intelligence. Note that proving anything of this nature would require some attention to the time-scale-dependence of the link weights in the transition graphs involved. A formally proved variant of the above proposition would be in short, a "MIND-WORLD CORRESPONDENCE THEOREM." Recall that at the start of the chapter, we expressed the same idea as: MIND-WORLD CORRESPONDENCE-PRINCIPLE For a mind to work intelligently toward certain goals in a certain world, there should be a nice mapping from goal-directed sequences of world-states into sequences of mind-states, where "nice" means that a world-state-sequence W composed of two parts W 1 and W 2 , gets mapped into a mind-state-sequence M composed of two corresponding parts M 1 and M 2 . That is a reasonable gloss of the principle, but it’s clunkier and less accurate, than the statement in terms of functors and path transfer functions, because it tries to use only commonlanguage vocabulary, which doesn’t really contain all the needed concepts. 10.5 How Might the Mind-World Correspondence Principle Be Useful? Suppose one believes the Mind-World Correspondence Principle as laid out above so what? Our hope, obviously, is that the principle could be useful in actually figuring out how to architect intelligent systems biased toward particular sorts of environment. And of course, this is said with the understanding that any finite intelligence must be biased toward some sorts of environment. Relatedly, given a specific AGI design (such as CogPrime), one could use the principle to figure out which environments it would be best suited for. Or one could figure out how to adjust the particulars of the design, to maximize the system’s intelligence in the environments of interest. One next step in developing this network of ideas, aside from (and potentially building on) full formalization of the principle, would be an exploration of real-world environments in terms of transition graphs. What properties do the transition graphs induced from the real world have? One such property, we suggest, is successive refinement. Often the path toward a goal involves first gaining an approximate understanding of a situation, then a slightly more accurate understanding, and so forth – until finally one has achieved a detailed enough understanding to actually achieve the goal. This would be represented by a world-path whose nodes are state-sets involving the gathering of progressively more detailed information. 182 10 A Mind-World Correspondence Principle Via pursuing to the mind-world correspondence property in this context, I believe we will find that world-paths reflecting successive refinement correspond to mind-paths embodying successive refinement. This will be found to relate to the hierarchical structures found so frequently in both the physical world and the human mind-brain. Hierarchical structures allow many relevant goals to be approached via successive refinement, which I believe is the ultimate reason why hierarchical structures are so common in the human mind-brain. Another next step would be exploring what mind-world correspondence means for the structure and dynamics of a limited-resources intelligence. If an organism O has limited resources and, to be intelligent, needs to make P (o(O, M(A), t(T ))|o(O, M(B), T )) high for particular world state-sets A and B, then what’s the organism’s best approach? Arguably, it should represent M(A) and M(B) internally in such a way that very little computational effort is required for it to transition between M(A) and M(B). For instance, this could be done by coding its knowledge in such a way that M(A) and M(B) share many common bits; or it could be done in other more complicated ways. If, for instance, A is a subset of B, then it may prove beneficial for the organism to represent M(A) physically as a subset of its representation of M(B). Pursuing this line of thinking, one could likely derive specific properties of an intelligent organism’s internal information-flow, from properties of the environment and goals with respect to which it’s supposed to be intelligent. This would allow us to achieve the holy grail of intelligence theory as I understand it: given a description of an environment and goals, to be able to derive an architectural description for an organism that will display a high level of intelligence relative to those goals, given limited computational resources. While this “holy grail” is obviously a far way off, what we’ve tried to do here is to outline a clear mathematical and conceptual direction for moving toward it. 10.6 Conclusion The Mind-World Correspondence Principle presented here – if in the vicinity of correctness – constitutes a non-trivial step toward fleshing out the concept of a general theory of general intelligence. But obviously the theory is still rather abstract, and also not completely rigorous. There’s a lot more work to be done. The Mind-World Correspondence Principle as articulated above is not quite a formal mathematical statement. It would take a little work to put in all the needed quantifiers to formulate it as one, and it’s not clear the best way to do so the details would perhaps become clear in the course of trying to prove a version of it rigorously. One could interpret the ideas presented in this chapter as a philosophical theory that hopes to be turned into a mathematical theory and to play a key role in a scientific theory. For the time being, the main role to be served by these ideas is qualitative: to help us think about concrete AGI designs like CogPrime in a sensible way. It’s important to understand what the goal of a real-world AGI system needs to be: to achieve the ability to broadly learn and generalize, yes, but not with infinite capability rather with biases and patterns that are implicitly and/or explicitly tuned to certain broad classes of goals and environments. The Mind-World 10.6 Conclusion 183 Correspondence Principle tells us something about what this "tuning" should involve – namely, making a system possessing mind-state sequences that correspond meaningfully to world-state sequences. CogPrime’s overall design and particular cognitive processes are reasonably well interpreted as an attempt to achieve this for everyday human goals and environments. One way of extending these theoretical ideas into a more rigorous theory is explored in Appendix ??. The key ideas involved there are: modeling multiple memory types as mathematical categories (with functors mapping between them), modeling memory items as probability distributions, and measuring distance between memory items using two metrics, one based on algorithmic information theory and one on classical information geometry. Building on these ideas, core hypotheses are then presented: • a syntax-semantics correlation principle, stating that in a successful AGI system, these two metrics should be roughly correlated • a cognitive geometrodynamics principle, stating that on the whole intelligent minds tend to follow geodesics (shortest paths) in mindspace, according to various appropriately defined metrics (e.g. the metric measuring the distance between two entities in terms of the length and/or runtime of the shortest programs computing one from the other). • a cognitive synergy principle, stating that shorter paths may be found through the composite mindspace formed by considering multiple memory types together, than by following the geodesics in the mindspaces corresponding to individual memory types. The material is relegated to an appendix because it is so speculative, and it’s not yet clear whether it will really be useful in advancing or interpreting CogPrime or other AGI systems (unlike the material from the present chapter, which has at least been useful in interpreting and tweaking the CogPrime design, even though it can’t be claimed that CogPrime was derived directly from these theoretical ideas). However, this sort of speculative exploration is, in our view, exactly the sort of thing that’s needed as a first phase in transitioning the ideas of the present chapter into a more powerful and directly actionable theory. Section III Cognitive and Ethical Development Chapter 11 Stages of Cognitive Development Co-authored with Stephan Vladimir Bugaj 11.1 Introduction Creating AGI, we have said, is not only about having the right structural and dynamical possibilities implemented in the initial version of one’s system – but also about the environment and embodiment that one’s system is associated with, and the match between the system’s internals and these externals. Another key aspect is the long-term time-course of the system’s evolution over time, both in its internals and its external interaction – i.e., what is known as development. Development is a critical topic in our approach to AGI because we believe that much of what constitutes human-level, human-like intelligence emerges in an intelligent system due to its engagement with its environment and its environment-coupled self-organization. So, it’s not to be expected that the initial version of an AGI system is going to display impressive feats of intelligence, even if the engineering is totally done right. A good analogy is the apparent unintelligence of a human baby. Yes, scientists have discovered that human babies are capable of interesting and significant intelligence – but one has to hunt to find it ... at first observation, babies are rather idiotic and simple-minded creatures: much less intelligent-appearing than lizards or fish, maybe even less than cockroaches.... If the goal of an AGI project is to create an AGI system that can progressively develop advanced intelligence through learning in an environment richly populated with other agents and various inanimate stimuli and interactive entities – then an understanding of the nature of cognitive development becomes extremely important to that project. Unfortunately, contemporary cognitive science contains essentially no theory of “abstract developmental psychology” which can conveniently be applied to understand developing AIs. There is of course an extensive science of human developmental psychology, and so it is a natural research program to take the chief ideas from the former and inasmuch as possible port them to the AGI domain. This is not an entirely simple matter both because of the differences between humans and AIs and because of the unsettled nature of contemporary developmental psychology theory. But it’s a job that must (and will) be done, and the ideas in this chapter may contribute toward this effort. We will begin here with Piaget’s well-known theory of human cognitive development, presenting it in a general systems theory context, then introducing some modifications and extensions and discussing some other relevant work. 187 188 11 Stages of Cognitive Development 11.2 Piagetan Stages in the Context of a General Systems Theory of Development Our review of AGI architectures in Chapter 4 focused heavily on the concept of symbolism, and the different ways in which different classes of cognitive architecture handle symbol representation and manipulation. We also feel that symbolism is critical to the notion of AGI development – and even more broadly, to the systems theory of development in general. As a broad conceptual perspective on development, we suggest that one may view the development of a complex information processing system, embedded in an environment, in terms of the stages: • automatic: the system interacts with the environment by “instinct”, according to its innate programming • adaptive: the system internally adapts to the environment, then interacting with the environment in a more appropriate way • symbolic: the system creates internal symbolic representations of itself and the environment, which in the case of a complex, appropriately structured environment, allows it to interact with the environment more intelligently • reflexive: the system creates internal symbolic representations of its own internal symbolic representations, thus achieving an even higher degree of intelligence Sketched so broadly, these are not precisely defined categories but rather heuristic, intuitive categories. Formalizing them would be possible but would lead us too far astray here. One can interpret these stages in a variety of different contexts. Here our focus is the cognitive development of humans and human-like AGI systems, but in Table 11.1 we present them in a slightly more general context, using two examples: the Piagetan example of the human (or humanlike) mind as it develops from infancy to maturity; and also the example of the “origin of life” and the development of life from proto-life up into its modern form. In any event, we allude to this more general perspective on development here mainly to indicate our view that the Piagetan perspective is not something ad hoc and arbitrary, but rather can plausibly be seen as a specific manifestation of more fundamental principles of complex systems development. 11.3 Piaget’s Theory of Cognitive Development The ghost of Jean Piaget hangs over modern developmental psychology in a yet unresolved way. Piaget’s theories provide a cogent overarching perspective on human cognitive development, coordinating broad theoretical ideas and diverse experimental results into a unified whole [Pia55]. Modern experimental work has shown Piaget’s ideas to be often oversimplified and incorrect. However, what has replaced the Piagetan understanding is not an alternative unified and coherent theory, but a variety of microtheories addressing particular aspects of cognitive development. For this reason a number of contemporary theorists taking a computer science [Shu03] or dynamical systems [Wit07] approach to developmental psychology have chosen to adopt the Piagetan framework in spite of its demonstrated shortcomings, both because of its conceptual strengths and for lack of a coherent, more rigorously grounded alternative. Our own position is that the Piagetan view of development has some fundamental truth to it, which is reflected via how nicely it fits with a broader view of development in complex systems. 11.3 Piaget’s Theory of Cognitive Development 189 Stage General Description Cognitive Development Origin of Life Automatic System-environment Piagetan infantile Self-organizing protolife information exchange stage system, e.g. Oparin controlled mainly by [Opa52] water droplet, innate system structures or Cairns-Smith [CS90] or environment clay-based protolife Adaptive Symbolic System-environment info exchange heavily guided by adaptively internally-created system structures Internal symbolic representation of information exchange process Reflexive Thoroughgoing selfmodification Piagetan based on this symbolic representation Piagetan “concrete operational” stage: systematic internal worldmodel guides worldexploration Piagetan formal stage: explicit logical/experimental learning about how to cognize in various contexts stage: purposive selfmodification of basic mental processes Simple autopoietic system, e.g. Oparin water droplet w/ basic metabolism Genetic code: internal entities that “stand for” aspects of organism and environment, thus enabling complex epigenesis post-formal Genes+memes: genetic code-patterns guide their own modification via influencing culture Table 11.1: General Systems Theory of Development: Parallels Between Development of Mind and Origin of Life Indeed, Piaget viewed developmental stages as emerging from general “algebraic” principles rather than as being artifacts of the particulars of human psychology. But, Piaget’s stages are probably best viewed as a general interpretive framework rather than a precise scientific theory. Our suspicion is that once the empirical science of developmental psychology has progressed further, it will become clearer how to fit the various data into a broad Piaget-like framework, perhaps differing in many details from what Piaget described in his works. Piaget conceived of child development in four stages, each roughly identified with an age group, and corresponding closely to the system-theoretic stages mentioned above: • infantile, corresponding to the automatic stage mentioned above – Example: Grasping blocks, piling blocks on top of each other, copying words that are heard • preoperational and concrete operational, corresponding to the adaptive stage mentioned above – Example: Building complex blocks structures, from imagination and from imitating objects and pictures and based on verbal instructions; verbally describing what has been constructed • formal, corresponding to the symbolic stage mentioned above – Example: Writing detailed instructions in words and diagrams, explaining how to construct particular structures out of blocks; figuring out general rules describing which sorts of blocks structures are likely to be most stable 190 11 Stages of Cognitive Development • the reflexive stage mentioned above corresponds to what some post-Piagetan theorists have called the post-formal stage – Example: Using abstract lessons learned from building structures out of blocks to guide the construction of new ways to think and understand – “Zen and the art of blocks building” (by analogy to Zen and the Art of Motorcycle Maintenance [Pir84]). Fig. 11.1: Piagetan Stages of Cognitive Development More explicitly, Piaget defined his stages in psychological terms roughly as follows: • Infantile: In this stage a mind develops basic world-exploration driven by instinctive actions. Reward-driven reinforcement of actions learned by imitation, simple associations between words and objects, actions and images, and the basic notions of time, space, and causality are developed. The most simple, practical ideas and strategies for action are learned. • Preoperational: At this stage we see the formation of mental representations, mostly poorly organized and un-abstracted, building mainly on intuitive rather than logical thinking. Word-object and image-object associations become systematic rather than occasional. Simple syntax is mastered, including an understanding of subject-argument relationships. One of the crucial learning achievements here is “object permanence” – infants learn that objects persist even when not observed. However, a number of cognitive failings persist with respect to reasoning about logical operations, and abstracting the effects of intuitive actions to an abstract theory of operations. • Concrete: More abstract logical thought is applied to the physical world at this stage. Among the feats achieved here are: reversibility – the ability to undo steps already done; conservation – understanding that properties can persist in spite of appearances; theory of mind – an understanding of the distinction between what I know and what others know (If 11.3 Piaget’s Theory of Cognitive Development 191 I cover my eyes, can you still see me?). Complex concrete operations, such as putting items in height order, are easily achievable. Classification becomes more sophisticated, yet the mind still cannot master purely logical operations based on abstract logical representations of the observational world. • Formal: Abstract deductive reasoning, the process of forming, then testing hypotheses, and systematically reevaluating and refining solutions, develops at this stage, as does the ability to reason about purely abstract concepts without reference to concrete physical objects. This is adult human-level intelligence. Note that the capability for formal operations is intrinsic in the PLN component of CogPrime, but in-principle capability is not the same as pragmatic, grounded, controllable capability. Very early on, Vygotsky [Vyg86] disagreed with Piaget’s explanation of his stages as inherent and developed by the child’s own activities, and Piaget’s prescription of good parenting as not interfering with a child’s unfettered exploration of the world. Some modern theorists have critiqued Piaget’s stages as being insufficiently socially grounded, and these criticisms trace back to Vygotsky’s focus on the social foundations of intelligence, on the fact that children function in a world surrounded by adults who provide a cultural context, offering ongoing assistance, critique, and ultimately validation of the child’s developmental activities. Vygotsky also was an early critic of the idea that cognitive development is continuous, and continues beyond Piaget’s formal stage. Gagne [RBW92] also believes in continuity, and that learning of prerequisite skills made the learning of subsequent skills easier and faster without regard to Piagetan stage formalisms. Subsequent researchers have argued that Piaget has merely constructed ad hoc descriptions of the sequential development of behaviour [Gib78, Bro84, CP05]. We agree that learning is a continuous process, and our notion of stages is more statistically constructed than rigidly quantized. Critique of Piaget’s notion of transitional “half stages” is also relevant to a more comprehensive hierarchical view of development. Some have proposed that Piaget’s half stages are actually stages [Bro84]. As Commons and Pekker [CP05] point out: “the definition of a stage that was being used by Piaget was based on analyzing behaviors and attempting to impose different structures on them. There is no underlying logical or mathematical definition to help in this process . . . ” Their Hierarchical Complexity development model uses task achievement rather than ad hoc stage definition as the basis for constructing relationships between phases of developmental ability – an approach which we find useful, though our approach is different in that we define stages in terms of specific underlying cognitive mechanisms. Another critique of Piaget is that one individual’s performance is often at different ability stages depending on the specific task (for example [GE86]). Piaget responded to early critiques along these lines by calling the phenomenon “horizontal décalage,” but neither he nor his successors [Fis80, Cas85] have modified his theory to explain (rather than merely describe) it. Similarly to Thelen and Smith [TS94], we observe that the abilities encapsulated in the definition of a certain stage emerge gradually during the previous stage – so that the onset of a given stage represents the mastery of a cognitive skill that was previously present only in certain contexts. Piaget also had difficulty accepting the idea of a preheuristic stage, early in the infantile period, in which simple trial-and-error learning occurs without significant heuristic guidance [Bic88], a stage which we suspect exists and allows formulation of heuristics by aggregation of learning from preheuristic pattern mining. Coupled with his belief that a mind’s innate abilities at birth are extremely limited, there is a troublingly unexplained transition from inability to ability in his model. 192 11 Stages of Cognitive Development Finally, another limiting aspect of Piaget’s model is that it did not recognize any stages beyond formal operations, and included no provisions for exploring this possibility. A number of researchers [Bic88, Arl75, CRK82, Rie73, Mar01] have described one or more postformal stages. Commons and colleagues have also proposed a task-based model which provides a framework for explaining stage discrepancies across tasks and for generating new stages based on classification of observed logical behaviors. [KK90] promotes a statistical conception of stage, which provides a good bridge between task-based and stage-based models of development, as statistical modeling allows for stages to be roughly defined and analyzed based on collections of task behaviors. [CRK82] postulates the existence of a postformal stage by observing elevated levels of abstraction which, they argue, are not manifested in formal thought. [CTS + 98] observes a postformal stage when subjects become capable of analyzing and coordinating complex logical systems with each other, creating metatheoretical supersystems. In our model, with the reflexive stage of development, we expand this definition of metasystemic thinking to include the ability to consciously refine one’s own mental states and formalisms of thinking. Such self-reflexive refinement is necessary for learning which would allow a mind to analytically devise entirely new structures and methodologies for both formal and postformal thinking. In spite of these various critiques and limitations, however, we have found Piaget’s ideas very useful, and in Section 11.4 we will explore ways of defining them rigorously in the specific context of CogPrime’s declarative knowledge store and probabilistic logic engine. 11.3.1 Perry’s Stages Also relevant is William Perry’s [Per70, Per81] theory of the stages (“positions” in his terminology) of intellectual and ethical development, which constitutes a model of iterative refinement of approach in the developmental process of coming to intellectual and ethical maturity. These stages, depicted in Table 11.2 form an analytical tool for discerning the modality of belief of an intelligence by describing common cognitive approaches to handling the complexities of real world ethical considerations. 11.3.2 Keeping Continuity in Mind Continuity of mental stages, and the fact that a mind may appear to be in multiple stages of development simultaneously (depending upon the tasks being tested), are crucial to our theoretical formulations and we will touch upon them again here. Piaget attempted to address continuity with the creation of transitional “half stages”. We prefer to observe that each stage feeds into the other and the end of one stage and the beginning of the next blend together. The distinction between formal and post-formal, for example, seems to “merely” be the application of formal thought to oneself. However, the distinction between concrete and formal is “merely” the buildup to higher levels of complexity of the classification, task decomposition, and abstraction capabilities of the concrete stage. The stages represent general trends in ability on a continuous curve of development, not discrete states of mind which are jumped-into quantum style after enough “knowledge energy” builds-up to cause the transition. 11.4 Piaget’s Stages in the Context of Uncertain Inference 193 Stage Substages Dualism / Received Basic duality (“All problems are solvable. I must learn the Knowledge [Infantile] correct solutions.”) Full dualism (“There are different, contradictory solutions to many problems. I must learn the correct solutions, and ignore the incorrect ones”) Multiplicity [Concrete] Relativism / Procedural Knowledge [Formal] Commitment / Constructed Knowledge [Formal / Reflexive] Early multiplicity (“Some solutions are known, others aren’t. I must learn how to find correct solutions.”) Late Multiplicity: cognitive dissonance regarding truth. (“Some problems are unsolvable, some are a matter of personal taste, therefore I must declare my own intellectual path.”) Contextual Relativism (“I must learn to evaluate solutions within a context, and relative to supporting observation.”) Pre-Commitment (“I must evaluate solutions, then commit to a choice of solution.”) Commitment (“I have chosen a solution.”) Challenges to Commitment (“I have seen unexpected implications of my commitment, and the responsibility I must take.”) Post-Commitment (“I must have an ongoing, nuanced relationship to the subject in which I evaluate each situation on a case-by-case basis with respects to its particulars rather than an ad-hoc application of unchallenged ideology.”) Table 11.2: Perry’s Developmental Stages [with corresponding Piagetan Stages in brackets] Observationally, this appears to be the case in humans. People learn things gradually, and show a continuous development in ability, not a quick jump from ignorance to mastery. We believe that this gradual development of ability is the signature of genuine learning, and that prescriptively an AGI system must be designed in order to have continuous and asymmetrical development across a variety of tasks in order to be considered a genuine learning system. While quantum leaps in ability may be possible in an AGI system which can just “graft” new parts of brain onto itself (or an augmented human which may someday be able to do the same using implants), such acquisition of knowledge is not really learning. Grafting on knowledge does not build the cognitive pathways needed in order to actually learn. If this is the only mechanism available to an AGI system to acquire new knowledge, then it is not really a learning system. 11.4 Piaget’s Stages in the Context of Uncertain Inference Piaget’s developmental stages are very general, referring to overall types of learning, not specific mechanisms or methods. This focus was natural since the context of his work was human developmental psychology, and neuroscience has not yet progressed to the point of understanding the neural mechanisms underlying any sort of inference (and certainly was nowhere near to doing so in Piaget’s time!). But if one is studying developmental psychology in an AGI context where one knows something about the internal mechanisms of the AGI system under consideration, then one can work with a more specific model of learning. Our focus here is on AGI systems whose operations contain uncertain inference as a central component. Obviously the main focus is CogPrime, but the essential ideas apply to any other uncertain inference centric AGI architecture as well. 194 11 Stages of Cognitive Development Fig. 11.2: Piagetan Stages of Development, as Manifested in the Context of Uncertain Inference An uncertain inference system, as we consider it here, consists of four components, which work together in a feedback-control loop 11.3 1. a content representation scheme 2. an uncertainty representation scheme 3. a set of inference rules 4. a set of inference control schemata Fig. 11.3: A Simplified Look at Feedback-Control in Uncertain Inference 11.4 Piaget’s Stages in the Context of Uncertain Inference 195 Broadly speaking, examples of content representation schemes are predicate logic and term logic [ES00]. Examples of uncertainty representation schemes are fuzzy logic [Zad78], imprecise probability theory [Goo86, FC86], Dempster-Shafer theory [Sha76, Kyb97], Bayesian probability theory [Kyb97], NARS [Wan95], and the Atom representation used in CogPrime, briefly alluded to in Chapter 6 above and described in depth in later chapters. Many, but not all, approaches to uncertain inference involve only a limited, weak set of inference rules (e.g. not dealing with complex quantified expressions). CogPrime’s PLN inference framework, like NARS and some other uncertain inference frameworks, contains uncertain inference rules that apply to logical constructs of arbitrary complexity. Only a system capable of dealing with constructs of arbitrary (or at least very high) complexity will have any potential of leading to human-level, human-like intelligence. The subtlest part of uncertain inference is inference control: the choice of which inferences to do, in what order. Inference control is the primary area in which human inference currently exceeds automated inference. Humans are not very efficient or accurate at carrying out inference rules, with or without uncertainty, but we are very good at determining which inferences to do and in what order, in any given context. The lack of effective, context-sensitive inference control heuristics is why the general ability of current automated theorem provers is considerably weaker than that of a mediocre university mathematics major [Mac95]. We now review the Piagetan developmental stages from the perspective of AGI systems heavily based on uncertain inference. 11.4.1 The Infantile Stage In this initial stage, the mind is able to recognize patterns in and conduct inferences about the world, but only using simplistic hard-wired (not experientially learned) inference control schema, along with pre-heuristic pattern mining of experiential data. In the infantile stage an entity is able to recognize patterns in and conduct inferences about its sensory surround context (i.e., it’s “world”), but only using simplistic, hard-wired (not experientially learned) inference control schemata. Preheuristic pattern-mining of experiential data is performed in order to build future heuristics about analysis of and interaction with the world. s tasks include: 1. Exploratory behavior in which useful and useless / dangerous behavior is differentiated by both trial and error observation, and by parental guidance. 2. Development of “habits” – i.e. Repeating tasks which were successful once to determine if they always / usually are so. 3. Simple goal-oriented behavior such as “find out what cat hair tastes like” in which one must plan and take several sequentially dependent steps in order to achieve the goal. Inference control is very simple during the infantile stage (Figure 11.4), as it is the stage during which both the most basic knowledge of the world is acquired, and the most basic of cognition and inference control structures are developed as the building block upon which will be built the next stages of both knowledge and inference control. Another example of a cognitive task at the borderline between infantile and concrete cognition is learning object permanence, a problem discussed in the context of CogPrime’s predecessor "Novamente Cognition Engine" system in [GPSL03]. Another example is the learning of 196 11 Stages of Cognitive Development Fig. 11.4: Uncertain Inference in the Infantile Stage word-object associations: e.g. learning that when the word “ball” is uttered in various contexts (“Get me the ball,” “That’s a nice ball,” etc.) it generally refers to a certain type of object. The key point regarding these “infantile” inference problems, from the CogPrime perspective, is that assuming one provides the inference system with an appropriate set of perceptual and motor ConceptNodes and SchemaNodes, the chains of inference involved are short. They involve about a dozen inferences, and this means that the search tree of possible PLN inference rules walked by the PLN backward-chainer is relatively shallow. Sophisticated inference control is not required: standard AI heuristics are sufficient. In short, textbook narrow-AI reasoning methods, utilized with appropriate uncertainty-savvy truth value formulas and coupled with appropriate representations of perceptual and motor inputs and outputs, correspond roughly to Piaget’s infantile stage of cognition. The simplistic approach of these narrow-AI methods may be viewed as a method of creating building blocks for subsequent, more sophisticated heuristics. In our theory Piaget’s preoperational phase appears as transitional between the infantile and concrete operational phases. 11.4.2 The Concrete Stage At this stage, the mind is able to carry out more complex chains of reasoning regarding the world, via using inference control schemata that adapt behavior based on experience (reasoning about a given case in a manner similar to prior cases). In the concrete operational stage (Figure 11.5), an entity is able to carry out more complex chains of reasoning about the world. Inference control schemata which adapt behavior based on experience, using experientially learned heuristics (including those learned in the prior stage), are applied to both analysis of and interaction with the sensory surround / world. Concrete Operational stage tasks include: 11.4 Piaget’s Stages in the Context of Uncertain Inference 197 Fig. 11.5: Uncertain Inference in the Concrete Operational Stage 1. Conservation tasks, such as conservation of number, 2. Decomposition of complex tasks into easier subtasks, allowing increasingly complex tasks to be approached by association with more easily understood (and previously experienced) smaller tasks, 3. Classification and Serialization tasks, in which the mind can cognitively distinguish various disambiguation criteria and group or order objects accordingly. In terms of inference control this is the stage in which actual knowledge about how to control inference itself is first explored. This means an emerging understanding of inference itself as a cognitive task and methods for learning, which will be further developed in the following stages. Also, in this stage a special cognitive task capability is gained: “Theory of Mind," which in cognitive science refers to the ability to understand the fact that not only oneself, but other sentient beings have memories, perceptions, and experiences. This is the ability to conceptually “put oneself in another’s shoes” (even if you happen to assume incorrectly about them by doing so). 11.4.2.1 Conservation of Number Conservation of number is an example of a learning problem classically categorized within Piaget’s concrete-operational phase, a “conservation laws” problem, discussed in [Shu03] in the context of software that solves the problem using (logic-based and neural net) narrow-AI techniques. Conservation laws are very important to cognitive development. Conservation is the idea that a quantity remains the same despite changes in appearance. If you show a child some objects and then spread them out, an infantile mind will focus on the spread, and believe that there are now more objects than before, whereas a concrete-operational mind will understand that the quantity of objects has not changed. Conservation of number seems very simple, but from a developmental perspective it is actually rather difficult. “Solutions” like those given in [Shu03] that use neural networks or cus- 198 11 Stages of Cognitive Development tomized logical rule-bases to find specialized solutions that solve only this problem fail to fully address the issue, because these solutions don’t create knowledge adequate to aid with the solution of related sorts of problems. We hypothesize that this problem is hard enough that for an inference-based AGI system to solve it in a developmentally useful way, its inferences must be guided by meta-inferential lessons learned from prior similar problems. When approaching a number conservation problem, for example, a reasoning system might draw upon past experience with set-size problems (which may be trial-and-error experience). This is not a simple “machine learning” approach whose scope is restricted to the current problem, but rather a heuristically guided approach which (a) aggregates information from prior experience to guide solution formulation for the problem at hand, and (b) adds the present experience to the set of relevant information about quantification problems for future refinement of thinking. Fig. 11.6: Conservation of Number For instance, a very simple context-specific heuristic that a system might learn would be: “When evaluating the truth value of a statement related to the number of objects in a set, it is generally not that useful to explore branches of the backwards-chaining search tree that contain relationships regarding the sizes, masses, or other physical properties of the objects in the set.” This heuristic itself may go a long way toward guiding an inference process toward a correct solution to the problem–but it is not something that a mind needs to know “a priori.” A concrete-operational stage mind may learn this by data-mining prior instances of inferences involving sizes of sets. Without such experience-based heuristics, the search tree for such a problem will likely be unacceptably large. Even if it is “solvable” without such heuristics, the solutions found may be overly fit to the particular problem and not usefully generalizable. 11.4.2.2 Theory of Mind Consider this experiment: a preoperational child is shown her favorite “Dora the Explorer” DVD box. Asked what show she’s about to see, she’ll answer “Dora.” However, when her parent plays the disc, it’s “SpongeBob SquarePants.” If you then ask her what show her friend will expect when given the “Dora” DVD box, she will respond “SpongeBob” although she just answered “Dora” for herself. A child lacking a theory of mind can not reason through what someone else would think given knowledge other than her own current knowledge. Knowledge of self is intrinsically related to the ability to differentiate oneself from others, and this ability may not be fully developed at birth. Several theorists [BC94, Fod94], based in part on experimental work with autistic children, perceive theory of mind as embodied in an innate module of the mind activated at a certain developmental stage (or not, if damaged). While we consider this possible, we caution against adopting a simplistic view of the “innate vs. acquired” dichotomy: if there is innateness it may take the form of an innate predisposition to certain sorts of learning [EBJ + 97]. 11.4 Piaget’s Stages in the Context of Uncertain Inference 199 Davidson [Dav84], Dennett [Den87] and others support the common belief that theory of mind is dependent upon linguistic ability. A major challenge to this prevailing philosophical stance came from Premack and Woodruff [PW78] who postulated that prelinguistic primates do indeed exhibit “theory of mind” behavior. While Premack and Woodruff’s experiment itself has been challenged, their general result has been bolstered by follow-up work showing similar results such as [TC97]. It seems to us that while theory of mind depends on many of the same inferential capabilities as language learning, it is not intrinsically dependent on the latter. There is a school of thought often called the Theory Theory [BW88, Car85, Wel90] holding that a child’s understanding of mind is best understood in terms of the process of iteratively formulating and refuting a series of naive theories about others. Alternately, Gordon [Gor86] postulates that theory of mind is related to the ability to run cognitive simulations of others’ minds using one’s own mind as a model. We suggest that these two approaches are actually quite harmonious with one another. In an uncertain AGI context, both theories and simulations are grounded in collections of uncertain implications, which may be assembled in contextappropriate ways to form theoretical conclusions or to drive simulations. Even if there is a special “mind-simulator” dynamic in the human brain that carries out simulations of other minds in a manner fundamentally different from explicit inferential theorizing, the inputs to and the behavior of this simulator may take inferential form, so that the simulator is in essence a way of efficiently and implicitly producing uncertain inferential conclusions from uncertain premises. We have thought through the details by CogPrime system should be able to develop theory of mind via embodied experience, though at time of writing practical learning experiments in this direction have not yet been done. We have not yet explored in detail the possibility of giving CogPrime a special, elaborately engineered “mind-simulator” component, though this would be possible; instead we have initially been pursuing a more purely inferential approach. First, it is very simple for a CogPrime system to learn patterns such as “If I rotated by pi radians, I would see the yellow block.” And it’s not a big leap for PLN to go from this to the recognition that “You look like me, and you’re rotated by pi radians relative to my orientation, therefore you probably see the yellow block.” The only nontrivial aspect here is the “you look like me” premise. Recognizing “embodied agent” as a category, however, is a problem fairly similar to recognizing “block” or “insect” or “daisy” as a category. Since the CogPrime agent can perceive most parts of its own “robot” body–its arms, its legs, etc.–it should be easy for the agent to figure out that physical objects like these look different depending upon its distance from them and its angle of observation. From this it should not be that difficult for the agent to understand that it is naturally grouped together with other embodied agents (like its teacher), not with blocks or bugs. The only other major ingredient needed to enable theory of mind is “reflection”– the ability of the system to explicitly recognize the existence of knowledge in its own mind (note that this term “reflection” is not the same as our proposed “reflexive” stage of cognitive development). This exists automatically in CogPrime, via the built-in vocabulary of elementary procedures supplied for use within SchemaNodes (specifically, the atTime and TruthValue operators). Observing that “at time T, the weight of evidence of the link L increased from zero” is basically equivalent to observing that the link L was created at time T. Then, the system may reason, for example, as follows (using a combination of several PLN rules including the above-given deduction rule): 200 11 Stages of Cognitive Development Implication My eye is facing a block and it is not dark A relationship is created describing the block’s color Similarity My body My teacher’s body |- Implication My teacher’s eye is facing a block and it is not dark A relationship is created describing the block’s color This sort of inference is the essence of Piagetan “theory of mind.” Note that in both of these implications the created relationship is represented as a variable rather than a specific relationship. The cognitive leap is that in the latter case the relationship actually exists in the teacher’s implicitly hypothesized mind, rather than in CogPrime’s mind. No explicit hypothesis or model of the teacher’s mind need be created in order to form this implication–the hypothesis is created implicitly via inferential abstraction. Yet, a collection of implications of this nature may be used via an uncertain reasoning system like PLN to create theories and simulations suitable to guide complex inferences about other minds. From the perspective of developmental stages, the key point here is that in a CogPrime context this sort of inference is too complex to be viably carried out via simple inference heuristics. This particular example must be done via forward chaining, since the big leap is to actually think of forming the implication that concludes inference. But there are simply too many combinations of relationships involving CogPrime’s eye, body, and so forth for the PLN component to viably explore all of them via standard forward-chaining heuristics. Experienceguided heuristics are needed, such as the heuristic that if physical objects A and B are generally physically and functionally similar, and there is a relationship involving some part of A and some physical object R, it may be useful to look for similar relationships involving an analogous part of B and objects similar to R. This kind of heuristic may be learned by experience–and the masterful deployment of such heuristics to guide inference is what we hypothesize to characterize the concrete stage of development. The “concreteness” comes from the fact that inference control is guided by analogies to prior similar situations. 11.4.3 The Formal Stage In the formal stage, as shown in Figure 11.7, an agent should be able to carry out arbitrarily complex inferences (constrained only by computational resources, rather than by fundamental restrictions on logical language or form) via including inference control as an explicit subject of abstract learning. Abstraction and inference about both the sensorimotor surround (world) and about abstract ideals themselves (including the final stages of indirect learning about inference itself) are fully developed. Formal stage evaluation tasks are centered entirely around abstraction and higher-order inference tasks such as: 1. Mathematics and other formalizations. 11.4 Piaget’s Stages in the Context of Uncertain Inference 201 Fig. 11.7: Uncertain Inference in the Formal Stage 2. Scientific experimentation and other rigorous observational testing of abstract formalizations. 3. Social and philosophical modeling, and other advanced applications of empathy and the Theory of Mind. In terms of inference control this stage sees not just perception of new knowledge about inference control itself, but inference controlled reasoning about that knowledge and the creation of abstract formalizations about inference control which are reasoned-upon, tested, and verified or debunked. 11.4.3.1 Systematic Experimentation The Piagetan formal phase is a particularly subtle one from the perspective of uncertain inference. In a sense, AGI inference engines already have strong capability for formal reasoning built in. Ironically, however, no existing inference engine is capable of deploying its reasoning rules in a powerfully effective way, and this is because of the lack of inference control heuristics adequate for controlling abstract formal reasoning. These heuristics are what arise during Piaget’s formal stage, and we propose that in the content of uncertain inference systems, they involve the application of inference itself to the problem of refining inference control. 202 11 Stages of Cognitive Development A problem commonly used to illustrate the difference between the Piagetan concrete operational and formal stages is that of figuring out the rules for making pendulums swing quickly versus slowly [IP58]. If you ask a child in the formal stage to solve this problem, she may proceed to do a number of experiments, e.g. build a long string with a light weight, a long string with a heavy weight, a short string with a light weight and a short string with a heavy weight. Through these experiments she may determine that a short string leads to a fast swing, a long string leads to a slow swing, and the weight doesn’t matter at all. The role of experiments like this, which test “extreme cases,” is to make cognition easier. The formal-stage mind tries to map a concrete situation onto a maximally simple and manipulable set of abstract propositions, and then reason based on these. Doing this, however, requires an automated and instinctive understanding of the reasoning process itself. The above-described experiments are good ones for solving the pendulum problem because they provide data that is very easy to reason about. From the perspective of uncertain inference systems, this is the key characteristic of the formal stage: formal cognition approaches problems in a way explicitly calculated to yield tractable inferences. Note that this is quite different from saying that formal cognition involves abstractions and advanced logic. In an uncertain logic-based AGI system, even infantile cognition may involve these – the difference lies in the level of inference control, which in the infantile stage is simplistic and hard-wired, but in the formal stage is based on an understanding of what sorts of inputs lead to tractable inference in a given context. 11.4.4 The Reflexive Stage In the reflexive stage (Figure 11.8), an intelligent agent is broadly capable of self-modifying its internal structures and dynamics. As an example in the human domain: highly intelligent and self-aware adult humans may carry out reflexive cognition by explicitly reflecting upon their own inference processes and trying to improve them. An example is the intelligent improvement of uncertain-truth-valuemanipulation formulas. It is well demonstrated that even educated humans typically make numerous errors in probabilistic reasoning [GGK02]. Most people don’t realize it and continue to systematically make these errors throughout their lives. However, a small percentage of individuals make an explicit effort to increase their accuracy in making probabilistic judgments by consciously endeavoring to internalize the rules of probabilistic inference into their automated cognition processes. In the uncertain inference based AGI context, what this means is: In the reflexive stage an entity is able to include inference control itself as an explicit subject of abstract learning (i.e. the ability to reason about one’s own tactical and strategic approach to modifying one’s own learning and thinking), and modify these inference control strategies based on analysis of experience with various cognitive approaches. Ultimately, the entity can self-modify its internal cognitive structures. Any knowledge or heuristics can be revised, including metatheoretical and metasystemic thought itself. Initially this is done indirectly, but at least in the case of AGI systems it is theoretically possible to also do so directly. This might be considered as a separate stage of Full Self Modification, or else as the end phase of the reflexive stage. In the context of logical reasoning, self modification of inference control itself is the primary task in this stage. In terms of inference control this 11.4 Piaget’s Stages in the Context of Uncertain Inference 203 Fig. 11.8: The Reflexive Stage stage adds an entire new feedback loop for reasoning about inference control itself, as shown in Figure 11.8. As a very concrete example, in later chapters we will see that, while PLN is founded on probability theory, it also contains a variety of heuristic assumptions that inevitably introduce a certain amount of error into its inferences. For example, PLN’s probabilistic deduction embodies a heuristic independence assumption. Thus PLN contains an alternate deduction formula called the “concept geometry formula” that is better in some contexts, based on the assumption that ConceptNodes embody concepts that are roughly spherically-shaped in attribute space. A highly advanced CogPrime system could potentially augment the independence-based and conceptgeometry-based deduction formulas with additional formulas of its own derivation, optimized to minimize error in various contexts. This is a simple and straightforward example of reflexive cognition – it illustrates the power accessible to a cognitive system that has formalized and reflected upon its own inference processes, and that possesses at least some capability to modify these. In general, AGI systems can be expected to have much broader and deeper capabilities for self-modification than human beings. Ultimately it may make sense to view the AGI systems we implement as merely "initial conditions" for ongoing self-modification and self-organization. Chapter ?? discusses some of the potential technical details underlying this sort of thoroughgoing AGI self-modification. Chapter 12 The Engineering and Development of Ethics Co-authored with Stephan Vladimir Bugaj and Joel Pitt 12.1 Introduction Most commonly, if a work on advanced AI mentions ethics at all, it occurs in a final summary chapter, discussing in broad terms some of the possible implications of the technical ideas presented beforehand. It’s no coincidence that the order is reversed here: in the case of CogPrime, AGI-ethics considerations played a major role in the design process ... and thus the chapter on ethics occurs near the beginning rather than the end. In the CogPrime approach, ethics is not a particularly distinct topic, being richly interwoven with cognition and education and other aspects of the AGI project. The ethics of advanced AGI is a complex issue with multiple aspects. Among the many issues there are: 1. Risks posed by the possibility of human beings using AGI systems for evil ends 2. Risks posed by AGI systems created without well-defined ethical systems 3. Risks posed by AGI systems with initially well-defined and sensible ethical systems eventually going rogue – an especially big risk if these systems are more generally intelligent than humans, and possess the capability to modify their own source code 4. the ethics of experimenting on AGI systems when one doesn’t understand the nature of their experience 5. AGI rights: in what circumstances does using an AGI as a tool or servant constitute “slavery” In this chapter we will focus mainly (though not exclusively) on the question of how to create an AGI with a rational and beneficial ethical system. After a somewhat wide-ranging discussion, we will conclude with eight general points that we believe should be followed in working toward "Friendly AGI" – most of which have to do, not with the internal design of the AGI, but with the way the AGI is taught and interfaced with the real world. While most of the particulars discussed in this book have nothing to do with ethics, it’s important for the reader to understand that AGI-ethics considerations have played a major role in many of our design decisions, underlying much of the technical contents of the book. As the materials in this chapter should make clear, ethicalness is probably not something that one can meaningfully tack onto an AGI system at the end, after developing the rest – it is likely infeasible to architect an intelligent agent and then add on an “ethics module.” Rather, ethics is something that has to do with all the different memory systems and cognitive processes that 205 206 12 The Engineering and Development of Ethics constitute an intelligent system – and it’s something that involves both cognitive architecture and the exploration a system does and the instruction it receives. It’s a very complex matter that is richly intermixed with all the other aspects of intelligence, and here we will treat it as such. 12.2 Review of Current Thinking on the Risks of AGI Before proceeding to outline our own perspective on AGI ethics in the context of CogPrime, we will review the main existing strains of thought on the potential ethical dangers associated with AGI. One science fiction film after another has highlighted these dangers, lodging the issue deep in our cultural awareness; unsurprisingly, much less attention has been paid to serious analysis of the risks in their various dimensions, but there is still a non-trivial literature worth paying attention to. Hypothetically, an AGI with superhuman intelligence and capability could dispense with humanity altogether – i.e. posing an "existential risk" [Bos02]. In the worst case, an evil but brilliant AGI, perhaps programmed by a human sadist, could consign humanity to unimaginable tortures (i.e. realizing a modern version of the medieval Christian visions of hell). On the other hand, the potential benefits of powerful AGI also go literally beyond human imagination. It seems quite plausible that an AGI with massively superhuman intelligence and positive disposition toward humanity could provide us with truly dramatic benefits, such as a virtual end to material scarcity, disease and aging. Advanced AGI could also help individual humans grow in a variety of directions, including directions leading beyond "legacy humanity," according to their own taste and choice. Eliezer Yudkowsky has introduced the term "Friendly AI", to refer to advanced AGI systems that act with human benefit in mind [Yud06]. Exactly what this means has not been specified precisely, though informal interpretations abound. Goertzel [Goe06b] has sought to clarify the notion in terms of three core values of Joy, Growth and Freedom. In this view, a Friendly AI would be one that advocates individual and collective human joy and growth, while respecting the autonomy of human choices. Some (for example, Hugo de Garis, [DG05]), have argued that Friendly AI is essentially an impossibility, in the sense that the odds of a dramatically superhumanly intelligent mind worrying about human benefit are vanishingly small. If this is the case, then the best options for the human race would presumably be to either avoid advanced AGI development altogether, or to else fuse with AGI before it gets too strongly superhuman, so that beings-originated-ashumans can enjoy the benefits of greater intelligence and capability (albeit at cost of sacrificing their humanity). Others (e.g. Mark Waser [Was09]) have argued that Friendly AI is essentially inevitable, because greater intelligence correlates with greater morality. Evidence from evolutionary and human history is adduced in favor of this point, along with more abstract arguments. Yudkowsky [Yud06] has discussed the possibility of creating AGI architectures that are in some sense "provably Friendly" – either mathematically, or else at least via very tight lines of rational verbal argumentation. However, several issues have been raised with this approach. First, it seems likely that proving mathematical results of this nature would first require dramatic advances in multiple branches of mathematics. Second, such a proof would require a formalization of the goal of "Friendliness," which is a subtler matter than it might seem [Leg06b, Leg06a]. 12.2 Review of Current Thinking on the Risks of AGI 207 Formalization of human morality has vexed moral philosophers for quite some time. Finally, it is unclear the extent to which such a proof could be created in a generic, environment-independent way – but if the proof depends on properties of the physical environment, then it would require a formalization of the environment itself, which runs up against various problems such as the complexity of the physical world and also the fact that we currently have no complete, consistent theory of physics. Kaj Sotala has provided a list of 14 objections to the Friendly AI concept, and suggested answers to each of them [Sot11]. Stephen Omohundro [Omo08] has argued that any advanced AI system will very likely demonstrate certain "basic AI drives", such as desiring to be rational, to self-protect, to acquire resources, and to preserve and protect its utility function and avoid counterfeit utility; these drives, he suggests, must be taken carefully into account in formulating approaches to Friendly AI. The problem of formally or at least very carefully defining the goal of Friendliness has been considered from a variety of perspectives, none showing dramatic success. Yudkowsky [Yud04] has suggested the concept of "Coherent Extrapolated Volition", which roughly refers to the extrapolation of the common values of the human race. Many subtleties arise in specifying this concept – e.g. if Bob Jones is often possessed by a strong desire to kill all Martians, but he deeply aspires to be a nonviolent person, then the CEV approach would not rate "killing Martians" as part of Bob’s contribution to the CEV of humanity. Goertzel [Goe10a] has proposed a related notion of Coherent Aggregated Volition (CAV), which eschews the subtleties of extrapolation, and simply seeks a reasonably compact, coherent, consistent set of values that is fairly close to the collective value-set of humanity. In the CAV approach, "killing Martians" would be removed from humanity’s collective value-set because it’s uncommon and not part of the most compact/coherent/consistent overall model of human values, rather than because of Bob Jones’ aspiration to nonviolence. One thought we have recently entertained is that the core concept underlying CAV might be better thought of as CBV or "Coherent Blended Volition." CAV seems to be easily misinterpreted as meaning the average of different views, which was not the original intention. The CBV terminology clarifies that the CBV of a diverse group of people should not be thought of as an average of their perspectives, but as something more analogous to a "conceptual blend" [FT02] – incorporating the most essential elements of their divergent views into a whole that is overall compact, elegant and harmonious. The subtlety here (to which we shall return below) is that for a CBV blend to be broadly acceptable, the different parties whose views are being blended must agree to some extent that enough of the essential elements of their own views have been included. The process of arriving at this sort of consensus may involve extrapolation of a roughly similar sort to that considered in CEV. Multiple attempts at axiomatization of human values have also been attempted, e.g. with a view toward providing near-term guidance to military robots (see e.g. Arkin’s excellent though chillingly-titled book Governing Lethal Behavior in Autonomous Robots [Ark09b], the result of US military funded research). However, there are reasonably strong arguments that human values (similarly to e.g. human language or human perceptual classification rules) are too complex and multifaceted to be captured in any compact set of formal logic rules. Wallach [WA10] has made this point eloquently, and argued the necessity of fusing top-down (e.g. formal logic based) and bottom-up (e.g. self-organizing learning based) approaches to machine ethics. A number of more sociological considerations also arise. It is sometimes argued that the risk from highly-advanced AGI going morally awry on its own may be less than that of moderatelyadvanced AGI being used by human beings to advocate immoral ends. This possibility gives 208 12 The Engineering and Development of Ethics rise to questions about the ethical value of various practical modalities of AGI development, for instance: • Should AGI be developed in a top-secret installation by a select group of individuals selected for a combination of technical and scientific brilliance and moral uprightness, or other qualities deemed relevant (a "closed approach")? Or should it be developed out in the open, in the manner of open-source software projects like Linux? (an "open approach"). The open approach allows the collective intelligence of the world to more fully participate – but also potentially allows the more unsavory elements of the human race to take some of the publicly-developed AGI concepts and tools private, and develop them into AGIs with selfish or evil purposes in mind. Is there some meaningful intermediary between these extremes? • Should governments regulate AGI, with Friendliness in mind (as advocated carefully by e.g Bill Hibbard [Hib02])? Or will this just cause AGI development to move to the handful of countries with more liberal policies? ... or cause it to move underground, where nobody can see the dangers developing? As a rough analogue, it’s worth noting that the US government’s imposition of restrictions on stem cell research, under President George W. Bush, appears to have directly stimulated the provision of additional funding for stem cell research in other nations like Korea, Singapore and China. The former issue is, obviously, highly relevant to CogPrime (which is currently being developed via the open source CogPrime project); and so the various dimensions of this issues are worth briefly sketching here. We have a strong skepticism of self-appointed elite groups that claim (even if they genuinely believe) that they know what’s best for everyone, and a healthy respect for the power of collective intelligence and the Global Brain, which the open approach is ideal for tapping. On the other hand, we also understand the risk of terrorist groups or other malevolent agents forking an open source AGI project and creating something terribly dangerous and destructive. Balancing these factors against each other rigorously, seems beyond the scope of current human science. Nobody really understands the social dynamics by which open technological knowledge plays out in our current world, let alone hypothetical future scenarios. Right now there exists open knowledge about many very dangerous technologies, and there exist many terrorist groups, yet these groups fortunately make scant use of these technologies. The reasons why appear to be essentially sociological – the people involved in these terrorist groups tend not to be the ones who have mastered the skills of turning public knowledge on cutting-edge technologies into real engineered systems. But while it’s easy to observe this sociological phenomenon, we certainly have no way to estimate its quantitative extent from first principles. We don’t really have a strong understanding of how safe we are right now, given the technology knowledge available right now via the Internet, textbooks, and so forth. Even relatively straightforward issues such as nuclear proliferation remain confusing, even to the experts. It’s also quite clear that keeping powerful AGI locked up by an elite group doesn’t really provide reliable protection against malevolent human agents. History is rife with such situations going awry, e.g. by the leadership of the group being subverted, or via brute force inflicted by some outside party, or via a member of the elite group defecting to some outside group in the interest of personal power or reward or due to group-internal disagreements, etc. There are many things that can go wrong in such situations, and the confidence of any particular group that they are immune to such issues, cannot be taken very seriously. Clearly, neither the open nor closed approach qualifies as a panacea. 12.3 The Value of an Explicit Goal System 209 12.3 The Value of an Explicit Goal System One of the subtle issues confronted in the quest to design ethical AGIs is how closely one wants to emulate human ethical judgment and behavior. Here one confronts the brute fact that, even according to their own deeply-held standards, humans are not all that ethical. One high-level conclusion we came to very early in the process of designing CogPrime is that, just as humans are not the most intelligent minds achievable, they are also not the most ethical minds achievable. Even if one takes human ethics, broadly conceived, as the standard – there are almost surely possible AGI systems that are much more ethical according to human standards than nearly all human beings. This is not mainly because of ethics-specific features of the human mind, but rather because of the nature of the human motivational system, which leads to many complexities that drive humans to behaviors that are unethical according to their own standards. So, one of the design decisions we made for CogPrime – with ethics as well as other reasons in mind – was not to closely imitate the human motivational system, but rather to craft a novel motivational system combining certain aspects of the human motivational system with other profoundly non-human aspects. On the other hand, the design of ethical AGI systems still has a lot to gain from the study of human ethical cognition and behavior. Human ethics has many aspects, which we associate here with the different types of memory, and it’s important that AGI systems can encompass all of them. Also, as we will note below, human ethics develops in childhood through a series of natural stages, parallel to and entwined with the cognitive developmental stages reviewed in Chapter 11 above. We will argue that for an AGI with a virtual or robotic body, it makes sense to think of ethical development as proceeding through similar stages. In a CogPrime context, the particulars of these stages can then be understood in terms of the particulars of CogPrime’s cognitive processes – which brings AGI ethics from the domain of theoretical abstraction into the realm of practical algorithm design and education. But even if the human stages of ethical development make sense for non-human AGIs, this doesn’t mean the particulars of the human motivational system need to be replicated in these AGIs, regarding ethics or other matters. A key point here is that, in the context of human intelligence, the concept of a "goal" is a descriptive abstraction. But in the AGI context, it seems quite valuable to introduce goals as explicit design elements (which is what is done in CogPrime ) – both for ethical reasons and for broader AGI design reasons. Humans may adopt goals for a time and then drop them, may pursue multiple conflicting goals simultaneously, and may often proceed in an apparently goal-less manner. Sometimes the goal that a person appears to be pursuing, may be very different than the one they think they’re pursuing. Evolutionary psychology [BDL93] argues that, directly or indirectly, all humans are ultimately pursuing the goal of maximizing the inclusive fitness of their genes – but given the complex mix of evolution and self-organization in natural history [Sal93], this is hardly a general explanation for human behavior. Ultimately, in the human context, "goal" is best thought of as a frequently useful heuristic concept. AGI systems, however, need not emulate human cognition in every aspect, and may be architected with explicit "goal systems." This provides no guarantee that said AGI systems will actually pursue the goals that their goal systems specify – depending on the role that the goal system plays in the overall system dynamics, sometimes other dynamical phenomena might intervene and cause the system to behave in ways opposed to its explicit goals. However, we submit that this design sketch provides a better framework than would exist in an AGI system closely emulating the human brain. 210 12 The Engineering and Development of Ethics We realize this point may be somewhat contentious – a counter-argument would be that the human brain is known to support at least moderately ethical behavior, according to human ethical standards, whereas less brain-like AGI systems are much less well understood. However, the obvious counter-counterpoints are that: • Humans are not all that consistently ethical, so that creating AGI systems potentially much more practically powerful than humans, but with closely humanlike ethical, motivational and goal systems, could in fact be quite dangerous • The effect on a human-like ethical/motivational/goal system of increasing the intelligence, or changing the physical embodiment or cognitive capabilities, of the agent containing the system, is unknown and difficult to predict given all the complexities involved The course we tentatively recommend, and are following in our own work, is to develop AGI systems with explicit, hierarchically-dominated goal systems. That is: • create one or more "top goals" (we call them Ubergoals in CogPrime ) • have the system derive subgoals from these, using its own intelligence, potentially guided by educational interaction or explicit programming • have a significant percentage of the system’s activity governed by the explicit pursuit of these goals Note that the "significant percentage" need not be 100%; CogPrime, for example, combines explicitly goal-directed activity with other "spontaneous" activity. Requiring that all activity be explicitly goal-directed may be too strict a requirement to place on AGI architectures. The next step, of course, is for the top-level goals to be chosen in accordance with the principle of human-Friendliness. The next one of our eight points, about the Global Brain, addresses one way of doing this. In our near-term work with CogPrime, we are using simplistic approaches, with a view toward early-stage system testing. 12.4 Ethical Synergy An explicit goal system provides an explicit way to ensure that ethical principles (as represented in system goals) play a significant role in guiding an AGI system’s behavior. However, in an integrative design like CogPrime the goal system is only a small part of the overall story, and it’s important to also understand how ethics relates to the other aspects of the cognitive architecture. One of the more novel ideas presented in this chapter is that different types of ethical intuition may be associated with different types of memory – and to possess mature ethics, a mind must display ethical synergy between the ethical processes associated with its memory types. Specifically, we suggest that: • Episodic memory corresponds to the process of ethically assessing a situation based on similar prior situations • Sensorimotor memory corresponds to “mirror neuron” type ethics, where you feel another person’s feelings via mirroring their physiological emotional responses and actions • Declarative memory corresponds to rational ethical judgment 12.4 Ethical Synergy 211 • Procedural memory corresponds to “ethical habit” ... learning by imitation and reinforcement to do what is right, even when the reasons aren’t well articulated or understood • Attentional memory corresponds to the existence of appropriate patterns guiding one to pay adequate attention to ethical considerations at appropriate times • Intentional memory corresponds to the pervasion of ethics through one’s choices about subgoaling (which leads into “when do the ends justify the means” ethical-balance questions) One of our suggestions regarding AGI ethics is that an ethically mature person or AGI must both master and balance all these kinds of ethics. We will focus especially here on declarative ethics, which corresponds to Kohlberg’s theory of logical ethical judgment; and episodic ethics, which corresponds to Gilligan’s theory of empathic ethical judgment. Ultimately though, all five aspects are critically important; and a CogPrime system if appropriately situated and educated should be able to master and integrate all of them. 12.4.1 Stages of Development of Declarative Ethics Complementing generic theories of cognitive development such as Piaget’s and Perry’s, theorists have also proposed specific stages of moral and ethical development. The two most relevant theories in this domain are those of Kohlberg and Gilligan, which we will review here, both individually and in terms of their integration and application in the AGI context. Lawrence Kohlberg’s [KLH83, Koh81] moral development model, called the “ethics of justice” by Gilligan, is based on a rational modality as the central vehicle for moral development. In our perspective this is a firmly declarative form of ethics, based on explicit analysis and reasoning. It is based on an impartial regard for persons, proposing that ethical consideration must be given to all individual intelligences without a priori judgment (prejudice). Consideration is given for individual merit and preferences, and the goals of an ethical decision are equal treatment (in the general, not necessarily the particular) and reciprocity. Echoing Kant’s [Kan64] categorical imperative, the decisions considered most successful in this model are those which exhibit “reversibility”, where a moral act within a particular situation is evaluated in terms of whether or not the act would be satisfactory even if particular persons were to switch roles within the situation. In other words, a situational, contextualized “do unto others as you would have them do unto you” criterion. The ethics of justice can be viewed as three stages (each of which has six substages, on which we will not elaborate here), depicted in Table 12.1. In Kohlberg’s perspective, cognitive development level contributes to moral development, as moral understanding emerges from increased cognitive capability in the area of ethical decision making in a social context. Relatedly, Kohlberg also looks at stages of social perspective and their consequent interpersonal outlook. As shown in Table 12.1, these are correlated to the stages of moral development, but also map onto Piagetian models of cognitive development (as pointed out e.g. by Gibbs [Gib78], who presents a modification/interpretation of Kohlberg’s ideas intended to align them more closely with Piaget’s). Interpersonal outlook can be understood as rational understanding of the psychology of other persons (a theory of mind, with or without empathy). Stage One, emergent from the infantile congitive stage, is entirely selfish as only self awareness has developed. As cognitive sophistication about ethical considerations increases, so do the moral and social perspective stages. Concrete and formal cognition bring about the first instrumental egoism, and then social relations and systems perspectives, and 212 12 The Engineering and Development of Ethics Stage Pre-Conventional Conventional Post-Conventional Substages • Obedience and Punishment Orientation • Self-interest orientation • Interpersonal accord (conformity) orientation • Authority and social-order maintaining (law and order) orientation • Social contract (human rights) orientation • Universal ethical principles (universal human rights) orientation Table 12.1: Kohlberg’s Stages of Development of the Ethics of Justice from formal and then reflexive thinking about ethics comes the post-conventional modalities of contractualism and universal mutual respect. Stage of Social Perspective Interpersonal Outlook Blind egoism No interpersonal perspective. Only self is considered. Instrumental egoism See that others have goals and perspectives, and either conform to or rebel against norms. Social Relationships Able to see abstract normative systems perspective Social Systems perspective Recognize positive and negative intentions Contractual perspective Recognize that contracts (mutually beneficial agreements of any kind) will allow intelligences to increase the welfare of both. Universal principle of See how human fallibility and frailty are impacted by communication. mutual respect Table 12.2: Kohlberg’s Stages of Development of Social Perspective and Interpersonal Morals 12.4.1.1 Uncertain Inference and the Ethics of Justice Taking our cue from the analysis given in Chapter 11 of Piagetan stages in uncertain inference based AGI systems (such as CogPrime ), we may explore the manifestation of Kohlberg’s stages in AGI systems of this nature. Uncertain inference seems generally well-suited as a declarative-ethics learning system, due to the nuanced ethical environment of real world situations. Probabilistic knowledge networks can model belief networks, imitative reinforcement learning based ethical pedagogy, and even simplistic moral maxims. In principle, they have the flexibility to deal with complex ethical decisions, including not only weighted “for the greater 12.4 Ethical Synergy 213 good” dichotomous decision making, but also the ability to develop moral decision networks which do not require that all situations be solved through resolution of a dichotomy. When more than one person is being affected by an ethical decision, making a decision based on reducing two choices to a single decision can often lead to decisions of dubious ethics. However, a sufficiently complex uncertain inference network can represent alternate choices in which multiple actions are taken that have equal (or near equal) belief weight but have very different particulars – but because the decisions are applied in different contexts (to different groups of individuals) they are morally equivalent. Though each individual action appears equally believable, were any single decision applied to the entire population one or more individual may be harmed, and the morally superior choice is to make case-dependent decisions. Equal moral treatment is a general principle, and too often the mistake is made by thinking that to achieve this general principle the particulars must be equal. This is not the case. Different treatment of different individuals can result in morally equivalent treatment of all involved individuals, and may be vastly morally superior to treating all the individuals with equal particulars. Simply taking the largest population and deciding one course of action based on the result that is most appealing to that largest group is not generally the most moral action. Uncertain inference, especially a complex network with high levels of resource access as may be found in a sophisticated AGI, is well suited for complex decision making resulting in a multitude of actions, and of analyzing the options to find the set of actions that are ethically optimal particulars for each decision context. Reflexive cognition and post-commitment moral understanding may be the goal stages of an AGI system, or any intelligence, but the other stages will be passed through on the way to that goal, and realistically some minds will never reach higher order cognition or morality with regards to any context, and others will not be able to function at this high order in every context (all currently known minds fail to function at the highest order cognitively or morally in some contexts). Infantile and concrete cognition are the underpinnings of the egoist and socialized stages, with formal aspects also playing a role in a more complete understanding of social models when thinking using the social modalities. Cognitively infantile patterns can produce no more than blind egoism as without a theory of mind, there is no capability to consider the other. Since most intelligences acquire concrete modality and therefore some nascent social perspective relatively quickly, most egoists are instrumental egoists. The social relationship and systems perspectives include formal aspects which are achieved by systematic social experimentation, and therefore experiential reinforcement learning of correct and incorrect social modalities. Initially this is a one-on-one approach (relationship stage), but as more knowledge of social action and consequences is acquired, a formal thinker can understand not just consequentiality but also intentionality in social action. Extrapolation from models of individual interaction to general social theoretic notions is also a formal action. Rational, logical positivist approaches to social and political ideas, however, are the norm of formal thinking. Contractual and committed moral ethics emerges from a higherorder formalization of the social relationships and systems patterns of thinking. Generalizations of social observation become, through formal analysis, systems of social and political doctrine. Highly committed, but grounded and logically supportable, belief is the hallmark of formal cognition as expressed contractual moral stage. Though formalism is at work in the socialized moral stages, its fullest expression is in committed contractualism. Finally, reflexive cognition is especially important in truly reaching the post-commitment moral stage in which nuance and complexity are accommodated. Because reflexive cognition is necessary to change one’s mind not just about particular rational ideas, but whole ways of 214 12 The Engineering and Development of Ethics thinking, this is a cognitive precedent to being able to reconsider an entire belief system, one that has had contractual logic built atop reflexive adherence that began in early development. If the initial moral system is viewed as positive and stable, then this cognitive capacity is seen as dangerous and scary, but if early morality is stunted or warped, then this ability is seen as enlightened. However, achieving this cognitive stage does not mean one automatically changes their belief systems, but rather that the mental machinery is in place to consider the possibilities. Because many people do not reach this level of cognitive development in the area of moral and ethical thinking, it is associated with negative traits (“moral relativism” and “flip-flopping”). However, this cognitive flexibility generally leads to more sophisticated and applicable moral codes, which in turn leads to morality which is actually more stable because it is built upon extensive and deep consideration rather than simple adherence to reflexive or rationalized ideologies. 12.4.2 Stages of Development of Empathic Ethics Complementing Kohlberg’s logic-and-justice-focused approach, Carol Gilligan’s [Gil82] “ethics of care” model is a moral development theory which posits that empathetic understanding plays the central role in moral progression from an initial self-centered modality to a socially responsible one. The ethics of care model is concerned with the ways in which an individual cares (responds to dilemmas using empathetic responses) about self and others. As shown in Table 12.3, the ethics of care is broken into the same three primary stage as Kohlberg, but with a focus on empathetic, emotional caring rather than rationalized, logical principles of justice. Stage Pre-Conventional Conventional Post-Conventional Principle of Care Individual Survival Self Sacrifice for the Greater Good Principle of Nonviolence (do not hurt others, or oneself) Table 12.3: Gilligan’s Stages of the Ethics of Care For an “ethics of care” approach to be applied in an AGI, the AGI must be capable of internal simulation of other minds it encounters, in a similar manner to how humans regularly simulate one another internally. Without any mechanism for internal simulation, it is unlikely that an AGI can develop any sort of empathy toward other minds, as opposed to merely logically or probabilistically modeling other agents’ behavior or other minds’ internal contents. In a CogPrime context, this ties in closely with how CogPrime handles episodic knowledge – partly via use of an internal simulation world, which is able to play “mental movies” of prior and hypothesized scenarios within the AGI system’s mind. However, in humans empathy involves more than just simulation, it also involves sensorimotor responses, and of course emotional responses – a topic we will discuss in more depth in Appendix ?? where we review the functionality of mirror neurons and mirror systems in the human brains. When we see or hear someone suffering, this sensory input causes motor responses in us similar to if we were suffering ourselves, which initiates emotional empathy and corresponding cognitive processes. 12.4 Ethical Synergy 215 Thus, empathic “ethics of care” involves a combination of episodic and sensorimotor ethics, complementing the mainly declarative ethics associated with the “ethics of justice.” In Gilligan’s perspective, the earliest stage of ethical development occurs before empathy becomes a consistent and powerful force. Next, the hallmark of the conventional stage is that at this point, the individual is so overwhelmed with their empathic response to others that they neglect themselves in order to avoid hurting others. Note that this stage doesn’t occur in Kohlberg’s hierarchy at all. Kohlberg and Gilligan both begin with selfish unethicality, but their following stages diverge. A person could in principle manifest Gilligan’s conventional stage without having a refined sense of justice (thus not entering Kohlberg’s conventional stage); or they could manifest Kohlberg’s conventional stage without partaking in an excessive degree of self-sacrifice (thus not entering Gilligan’s conventional stage). We will suggest below that in fact the empathic and logical aspects of ethics are more unified in real human development than these separate theories would suggest. However, even if this is so, the possibility is still there that in some AGI systems the levels of declarative and empathic ethics could wildly diverge. It is interesting to note that Gilligan’s and Kohlberg’s final stages converge more closely than their intermediate ones. Kohlberg’s post-conventional stage focuses on universal rights, and Gilligan’s on universal compassion. Still, the foci here are quite different; and, as will be elaborated below, we believe that both Kohlberg’s and Gilligan’s theories constitute very partial views of the actual end-state of ethical advancement. 12.4.3 An Integrative Approach to Ethical Development We feel that both Kohlberg’s and Gilligan’s theories contain elements of the whole picture of ethical development, and that both approaches are necessary to create a moral, ethical artificial general intelligence – just as, we suggest, both internal simulation and uncertain inference are necessary to create a sufficiently intelligent and volitional intelligence in the first place. Also, we contend, the lack of direct analysis of the underlying psychology of the stages is a deficiency shared by both the Kohlberg and Gilligan models as they are generally discussed. A successful model of integrative ethics necessarily contains elements of both the care and justice models, as well as reference to the underlying developmental psychology and its influence on the character of the ethical stage. Furthermore, intentional and attentional ethics need to be brought into the picture, complementing Kohlberg’s focus on declarative knowledge and Gilligan’s focus on episodic and sensorimotor knowledge. With these notions in mind, we propose the following integrative theory of the stages of ethical development, shown in Tables 12.4, 12.5 and 12.6. In our integrative model, the justicebased and empathic aspects of ethical judgment are proposed to develop together. Of course, in any one individual, one or another aspect may be dominant. Even so, however, the combination of the two is equally important as either of the two individual ingredients. For instance, we suggest that in any psychologically healthy human, the conventional stage of ethics (typifying childhood, and in many cases adulthood as well) involves a combination of Gilligan-esqe empathic ethics and Kohlberg-esque ethical reasoning. This combination is supported by Piagetan concrete operational cognition, which allows moderately sophisticated linguistic interaction, theory of mind, and symbolic modeling of the world. And, similarly, we propose that in any truly ethically mature human, empathy and rational justice are both fully developed. Indeed the two interpenetrate each other deeply. 216 12 The Engineering and Development of Ethics Once one goes beyond simplistic, childlike notions of fairness (“an eye for an eye” and so forth), applying rational justice in a purely intellectual sense is just as difficult as any other real-world logical inference problem. Ethical quandaries and quagmires are easily encountered, and are frequently cut through by a judicious application of empathic simulation. On the other hand, empathy is a far more powerful force when used in conjunction with reason: analogical reasoning lets us empathize with situations we have never experienced. For instance, a person who has never been clinically depressed may have a hard time empathizing with individuals who are; but using the power of reason, they can imagine their worst state of