An overview of computation and the mind

[Brief summary of this post]

I grew up in the 60’s and 70’s with a tacit understanding that thinking was computing and that artificial intelligence was right around the corner. Fifty years later we have algorithms that can simulate some mental tasks, but nothing close to artificial intelligence, and no good overall explanation of how we think. Why is that? It’s just that the problem is harder than we first thought. We will get there, but we need to get a better grasp of what the problem is and what would qualify as a solution. Our accomplishments over seventy or so years of computing include developing digital computers, making them much faster, demonstrating that they can simulate anything requiring computation, and devising some nifty algorithms. Evolution, on the other hand, has spent over 550 million years working on the mind. Because it is results-oriented, it has simultaneously developed better hardware and software to deliver minds most capable of keeping animals alive. The “hardware” includes the neurons and their electrochemical mechanisms, and the “software” includes a memory of things, events, and behaviors that supports learning from experience. If the problem we are trying to solve is to use computers to perform tasks that only humans have been able to do, then we have laid all the groundwork. More and more algorithms that can simulate many human accomplishments will appear as our technology improves. But my interest is in explaining how the brain manages information to solve problems and why and how brains have minds. To solve that problem, let’s take a top-down or reverse-engineered view of computation.

Computation is not just manipulation of numbers by rules or data by instructions. More abstractly, the functional conception of computation is a process performed on inputs that yields outputs that can be used to reduce uncertainty, which can be used in feedback loops to achieve predictable outcomes. Any input or output that can reduce uncertainty is said to contain information. White noise is data that is completely free of usable information. Minds, in particular, are computers because they use inputs from the environment and their own experience to produce output actions that facilitate their survival. If we agree that minds are processing information in this way, and exclude the possibility that supernatural forces assist them, then we can conclude that we need a computational theory of mind (CTM) to explain them.

Reverse engineering all the algorithms used by the brain down to the hardware and software mechanisms that support them is a large project. My focus is a top-down explanation, so I am going to focus just on the algorithms involved at the highest level of control that decide what we do. Most of the hard work, from a computational perspective, happens at the lower levels, so we will need to have a sense of what those levels are doing, but we won’t need to consider too closely how they do it. This is good because we don’t know much about the mechanics of brain function yet. What we do know doesn’t explain how it works so much as provide physical constraints with which any explanatory theory must be consistent. I will discuss some of those constraints in later in The process of mind.

At this point, I have to ask you to take a computational leap of faith with me. I will try to justify it as we go, but it is a hard point to prove, so once the groundwork has been laid we will have to evaluate whether we have enough evidence to prove it. The leap is this: the mind makes top-level decisions by reasoning with meaningful representations. This leap has a fascinating corollary: consciousness only exists to help this top-level representational decision-making process. Intuitively, this makes a lot of sense — we know we reason by considering propositions that have meaning to us, and we feel such reasoning directly supports many of our decisions. And our feeling of awareness or consciousness seems to be closely related to how we make decisions. But I need to explain what I mean by this from an objective point of view.

The study of meaning is called semantics. Semantics defines meaning in terms of the relationship between symbols, also called signifiers or representation, and what they refer to, also called referents or denotation. A model of the mind based on these kinds of relationships is called a representational theory of mind (RTM). I propose that these relationships form the meaningful representations that are the basis of all top-level reasoned decisions. I do not propose that everything in the mind is representational; most of what the mind does and experiences is not representational. RTM only applies to this top-level reasoning process. Some examples of information processing that are not representational include raw sensory perception, habitual behavior, and low-level language processing. To the extent we feel our senses without forming any judgments those feelings are free of meaning; they just are. So instrumental music consequently has no meaning. And to the extent we behave in a rote fashion, performing an action based on intuition or learned behavior without forming judgments, those actions are free of meaning, they just happen. Perhaps when we learned those behaviors we did form judgments, and if we recall those judgments when we use the behaviors then there is some residual meaning, but the meaning has become irrelevant and can be, and often will be, forgotten. People who tie their shoelaces by rote with no notion as to why the actions produce a knot have no detailed representation of knots; they just know they will end up with a knot. So much “intelligent” or at least clever behavior can take place without meaning. Finally, although language a critical tool, perhaps the critical tool, in supporting representational reasoning, as words and sentences can be taken as directly representing concepts and propositions, it only achieves this success through subconscious skills that understand grammar and tie concepts to words.

Importantly, just as we can tie knots by rote, we could, in theory, live our whole lives by rote without reasoning with represented objects (i.e. concepts) and, consequently, without conscious awareness. We would first need to be trained how to handle every situation we might encounter. While we don’t know how we could do that for people, we can train computers using an approach called machine learning. By training a self-driving car using feedback from millions of real-life examples, the algorithm can be refined to solve the driving problem from a practical standpoint without representation. Sure, the algorithm could not do as well as a human in entirely new conditions. For example, a human driver could quickly adapt to driving on the left side of the road in England, but the self-driving car might need special programming to flip its perspective. Also note that such algorithms do typically use representation for some elements, e.g. vehicles and pedestrians. But they don’t reason using these objects; they just use them to look up the best learned behaviors. So some algorithmic use of representation is not the same as using representation to support reasoning.

People can’t live their lives entirely by rote as we encounter novel situations almost continuously, so learned behavior is used more as another input to the reasoning process than as a substitute for it. Perhaps Mother Nature could have devised another way for us to solve problems as flexibly as reasoning can, but if so, we don’t know what that way might be. Furthermore, we appear quite unable to take actions that are the product of our top-level reasoning without explicit conscious awareness and attention in the full subjective theater of our minds. This experience, in surround-sound technicolor, is not at all incidental to the reasoning process but exists to provide reasoning with the most relevant information at all times.

Note that language is entirely representational by its very nature. Every word represents something. Just what words represent is more complex. Words are a window into both representational and nonrepresentational knowledge. They can be used in a highly formalized way to represent specific concepts and propositions about them in a logical, reasoned way. Or they can be used more poetically to represent feelings, impressions or mood. In practice, they will evoke different concepts and connotations in different people in different contexts as our minds interpret language at both conscious and subconscious levels. My focus on language will be more toward the rational support it provides consciousness to support reasoning with concepts, many of which represent things or relationships in the real world.

The top-down theory of mind (TDTM) I am proposing says that all mental functions use CTM, but only some processes use RTM. Further, I propose that consciousness exists to support reasoning, which critically depends on RTM while also seamlessly integrating with nonrepresentational mental capacities. While I am not going to review other theories at this time, conventional RTM theories propose that meaning ends with representation, while I say it is only the outer layer of the onion. Similarly, associative or connectionist theories explain memory and learned behavior with limited or no use of representation, as I have above, but do not propose a process that can compete with reasoning.

While the above provides some objective basis for reasoning as a flexible mental tool and consciousness as a way to efficiently present relevant information to the reasoning process, it does not say why we experience consciousness the way we do. We know we strive tenaciously and are fairly convinced, if we ask ourselves why, that it is because we have desires. That is, it is not because we know we have to survive and reproduce to satisfy evolution, but because the things we want to do usually include living and procreating. So apparently, working on behalf of our desires is a subjective equivalent to the objective struggle for survival. But why do we want things instead of just selecting actions that will best propagate our genes? Why does it feel like we’ve each got a quarter in the greatest video game ever made, a virtual reality first-person shooter that takes virtual reality to a whole new level — let’s call it “immersive reality” — in which we are not just playing the game, we are the game? Put simply, it is because life is a game, so it has to play like one. A game is an activity with goals, rules, challenges, and interaction. The imperatives of evolution create the goals and rules evolve around them. But the rules that develop are abstract ideas that don’t need a physical basis; they just need to get the job done.

The game of life has one main goal: survive. Earth’s competitive environment added a critical subgoal: perform at the highest level of efficiency and efficacy. And sexual selection, whose high evolutionary cost seems to be offset by the benefit of greater variation, led to the goal of sexual reproduction. But what could make animals pursue these goals with gusto? The truth is, animals don’t need to know what the goals are, they just need to act in such a way that they are attained. You could say theirs not to reason why, theirs but to do and die, in the sense that it doesn’t help animals in their mission to know why they eat certain foods, struggle relentlessly, or select certain mates. But it is crucial that they eat just the right amount of the foods that best sustain them and select the fittest mates. This is the basis of our desires. They are, objectively, nothing more than rules instructing us to prioritize certain behaviors to achieve certain goals. We are not innately aware of the ultimate goals, although as humans who have figured out how natural selection works, we now know what they are.

Our desires don’t force our hand; they only encourage us to prioritize our actions appropriately. We develop propositions about them that exist for us just as much as physical objects; they are part of our reality, which is a combination of physical and ideal. Closely held propositions are called beliefs. Beliefs founded in desires are subjective beliefs while beliefs founded in sensory perception are objective beliefs. Subjective beliefs could never be proven (as desires are inherently variable), but objective beliefs are verifiable. We learn strategies to fulfill desires. We learn many elements of the strategies we use to fulfill our most basic desires by following innate cues (instincts) for skills like mimicry, chewing, breathing, and so on. While we later develop conscious and reasoning control over these mostly innate strategies, it is only to act as a top-level supervisory capacity. So discussions of this top reasoning level are not intended to overlook the significance of well-developed underlying mechanisms that do the “real work”, much the way a company can function fairly well for a while without its CEO. With that caveat in mind, when we apply logical rules to propositions based on our senses, desires, and beliefs the implications spell out our actions. After we have developed detailed strategies for eating and mating, we still need to apply conscious reasoning all the time to apply prioritization to that cacophony of possibilities. We don’t need to know our evolutionary goals because our desires and the beliefs and strategies that follow from them are extremely well tuned to lead us to behaviors that will fulfill them.

Desires are fundamentally nonrepresentational in that they are experienced viscerally on a scale with greater or lesser force. They are not qualia themselves but the degree to which each quale appeals to us, which varies as a function of our metabolic state. So when we feel cold, we want warmth, and when we feel hunger, we want food. They are aids to prioritization and steer the decision-making process (both through reasoning and at levels below that). To reason with desires and subjective beliefs, we interpret them as weighted propositions using probabilistic logic. Because all relevant beliefs, desires, sensory qualia and memories are processed concurrently by consciousness, they all contribute to a continuous prioritization exercise that allows us to accomplish many goals appropriately despite having a serial instrument (one body). In other words, we have distinct qualia and as needed desires for them for the express purpose of ensuring all the relevant data is on the table before we make each decision.

So what is consciousness, exactly? Consciousness is a segregated aspect of the mind that uses qualia, memory, and expertise to make reasoned decisions. From a computational perspective, this means it is a subroutine fed data through custom data channels (in both nonrepresentational and representational ways) that has customized ways to process it. The nonrepresentational forms support whims or intuitions, and the representational forms support reasoned decisions. Importantly, reason has the last word; we can’t act, or at least not for very long, without support from our reasoning minds. Conversely, the conscious mind doesn’t exactly act itself, it delegates actions to the subconscious for execution, analogously to a manager and his employees. From a subjective perspective, the segregation of consciousness from the rest of the mind creates the subjective perspective or theater of mind. It seems to us to be a seamless projection of the external world into our heads because it is supposed to. We interpret what is actually a jumble of qualia as a smoothly flowing movie because the mandate to continuously prioritize and decide requires that we commit to the representation being the reality. To hesitate in accepting imagination as reality would lead to frequent and costly delays and mistakes. We consequently can’t help but believe that the world that floods into our conscious minds on qualia channels is real. It is not physically real, of course, but wetware really is running a program in our minds and that is real, so we can say that the world of our imagination, our conduit to the ideal world, is real as well, though in a different way.

Our objective beliefs, supported by our sensory qualia and memory, meet a very high objective standard, while our subjective beliefs, supported by our desires, are self-serving and only internally verifiable. Because our selfish needs often overlap with those of others and the ecosystem at large, they can often be fulfilled without stepping on any toes, but competition is an inescapable part of the equation. Our subjective beliefs give us a framework for prioritizing our interactions with others based entirely on abstracted preferences rather than literal evolutionary goals, based on desires tuned by evolution to achieve those goals. In other words, blindly following our subjective beliefs should result in self-preservation and the preservation of our communities and ecosystems. However, humans face a special challenge because we are no longer in the ancestral environment for which our desires are tuned, and we have free will and know how to use it. While this is a potential recipe for disaster, we will ultimately best satisfy our desires by artificially realigning them with evolutionary objectives. While our desires are immutable, the beliefs and strategies we develop to fulfill them are open to interpretation. In other words, we can use science and other tools of reasoning to help us adjust our subjective beliefs, through laws if necessary, to fulfill our desires in a way that is compatible with a sustainable future.

I call the portion of the conscious mind dedicated to reasoning the “single stream step selector”, or SSSS. While “just” a subprocess of the mind, it is the part of our conscious minds that we identify with most. The SSSS exercises free will in making decisions in both a subjective and objective sense. Subjectively we feel we are freely selecting from among possible worlds. We are also objectively free in a few ways, most significantly because our behavior is unpredictable, being driven by partially chaotic forces in our brains. Secondly, and more significantly to us as intelligent beings, our actions are optimized selections leveraging information management, i.e. computation, which doesn’t happen by chance or in simple natural systems. So without violating the determinism of the universe we nevertheless make things happen that would never happen without huge computational help.

The process of making decisions is much more involved than simply weighing propositions. Propositions in isolation are meaningless. What gives them meaning is context. Computationally, context is all the relationships between all the symbols used by the propositions. These relationships are the underlying propositions that set the ground rules for the propositions in question. Subjectively, a context is a model or possible world. Whenever we imagine a situation working according to certain rules, we have established a model in our minds. If the rules are somewhat flexible or not nailed down, this can be thought of as establishing a range of models. We keep a primary model (really a set of models covering different aspects) for the way we think the world actually is. We create future models for the ways we think things might go. We expect one of those future models to become real, in the sense that it should in time line up with the actual present within our limits of accuracy and detail. We keep a past model (again, really a set) for the way we think things were. Internally, our models support considerable flexibility, and we adapt them all the time as new information becomes available. Externally, at the moment we decide to do something, we have committed to a specific model and its implications. That model itself can be a weighted combination of several models that may be complementary or antagonistic to each other, but in any case, we are taking a stand. We have done an evaluation, either off the cuff or with deep forethought, of all the relevant information, using as many models as seem relevant to the situation and building new models we haven’t used before as we go if needed.

Viewed abstractly, what the mind is creating inside is a different kind of universe, a mental one instead of a physical one. Our mental universe is a special case of an ideal universe, in which ideas comprise reality. One could argue that the conscious and subconscious realms comprise distinct ideal universes which overlap in places. And one could argue that mathematical systems and scientific theories and our own models each comprise their own ideal world, bound by the rules that define them. Ideal worlds can be interesting in their own right for reasons abstracted from practical application, but their primary role is to help us predict real world behavior. To do this, we have to establish a mapping or correlation between the model and what we observe. Processing feedback from our observations and actions is called learning. We are never fully convinced our methods are perfect, so we are always evaluating how well they work and refining them. This approach of continuous improvement was successfully applied by Toyota (where it is called kaizen), but we do it automatically. It is worth noting at this point that the above argument solves the classic mind-body problem of how mental states are related to physical states, that is, how the contents of our subjective lives relate to the physical world. The answer I am proposing, a union of an ideal universe and a physical one, goes beyond this discussion on computation, but I will speak more on it later.

We have no access to our own programming and can only guess how the program is organized. But that’s ok; we are designed to function without knowing how the programming works or even that we are a program. We experience the world as our programming dictates: we strive because we are programmed to strive, and our whole UI (user interface) is organized to inspire us to relentlessly select steps that will optimize our chances of staying in the game. “Inspire” is the critical word here, meaning both “to fill with an animating, quickening, or exalting influence” (as a subjective word) and “to breathe in” (as an objective word). Is it a mystical force or a physical action? It sits at the confluence of the mental and physical worlds, capturing the essence of our subjective experience of being in the world and our physical presence in the world that comes one breath at a time. The physical part seems easy enough to understand, but what is the subjective part?

How does a program make the world feel the way it does to us? Yes, it’s an illusion. Nothing in the mind is real, after all, so it has to be an illusion. But it is not incidental or accidental. It all stems from the simple fact that animals can only do one thing at a time (or at least their bodies can only engage in one coordinated set of actions at a time). Most of all, they can’t be in two places at the same time. The SSSS must take one step at a time, and then again in an endless stream. But why should this requirement lead to the creation of a subjective perspective with a theater of mind? It follows from the way logic works. Logic works with propositions, not with raw data from the real world. The real world itself does not run by reasoning through logical propositions; it works simply because a lot of particles move about on their own trajectories. Although we believe they obey strict physical laws, their movements can’t be perfectly foretold. First, it would violate the Heisenberg Uncertainty Principle to know the exact position and bearing of each particle, as that would eclipse their wave-like nature. And secondly, the universe is happening but not “watching itself happen”. This argument, called Laplace’s demon, is the idea that someone (the demon) who knew the precise location and momentum of every atom in the universe could predict the future. It is now considered impossible on several grounds. But while the physical universe precludes exact prediction, it does not preclude approximate prediction, and it is through this loophole that the concept of a reasoning mind starts to emerge.

Think back to the computational leap I am trying to prove: the mind makes top-level decisions by reasoning with meaningful representations. I can’t prove that reasoning is the only way to control bodies at the top level, but I have argued above that it is the way we do it. But how exactly can reasoning help in a world of particles? It starts, before reasoning enters the picture, with generalization. The symbols we represent don’t exist as such in the physical world. We represent physical objects with idealized representations (called concepts) that include the essential characteristics of those objects. Generalization is the ability to recognize patterns and to group things, properties, and ideas into categories reflecting that similarity. It is probably the most important and earliest of all mental skills. But it carries a staggering implication: it shapes the way minds interpret the world. We have a simplified, stripped down view of the world, which could fairly be called a cartoon, that subdivides it into logical components (concepts, which include objects and actions) around which simple deductions can be made to direct a single body. While my thrust is to describe how these generalized representations support reason, they also support associative approaches like intuition and learned behavior. The underlying mechanism is feedback: generalized information about past patterns can help predict what patterns will happen again.

Reasoning takes the symbols formed from generalized representations and develops propositions about them to create logical scenarios called models or possible worlds. Everything I have written above drives to this point. A model is an idealization with two kinds of existence, ideal and physical, which are independent. For example, 1+1=2 according to some models of arithmetic, and this is objectively and unalterably true, independent of the physical world or even our ability to think it. Ideal existence is a function of relationships. On the other hand, a model can physically exist using a computer (e.g. biological or silicon) to implements it, or on paper or other recorded form which could later be interpreted by a computer. Physical existence is a function of spacetime, which in this case takes the form of a set of instructions in a computer. To use models, we need to expect that the physical implementation is done well so that we can focus on what the model says ideally. In other words, we need a good measure of trust in the correlation from the ideal representation to the physical referent. While we are not stupid and we know that perception is not reality, we are designed to trust the theater we interact with implicitly, both because it spares us from excess worry and because that correlation is very dependable in practice.

The ideal and physical worlds are independent of each other and might always have remained so were it not for the emergence of the animal mind some 550 million years ago. The upgrades we received in the past 4 million years with the rise of the Australopithecus and Homo genera are the most ambitious improvements in a long time, but animal minds were already quite capable. We’re just version 10.03 or so in a long line of impressive earlier releases. Animal minds probably all model the world using representation, which, as noted, captures the essential characteristics of referents, as well as rules about how objects and their properties behave relative to each other in the model. Computationally, minds use data structures that represent the world in a generalized or approximate way by recording just the key properties. All representations are formed by generalizing, but while some remain general (as with common nouns), some are tracked as specific instances (and optionally named, as with proper nouns). For that matter, generalizations can be narrow or broad for detailed or summary treatments of situations. For any given circumstance the mind draws together the concepts (being the objects and their characteristics) that seem relevant to the level of detail at hand so it can construct propositions and draw logical conclusions in a single stream. We weigh propositions using probabilistic logic and consider multiple models for every situation, which improves our flexibility. This analysis creates the artificial world of our conscious experience, the cartoon. This simplified logical view seamlessly overlays with our sensory perceptions, which pull the quality of the experience up from a cartoon to photorealistic quality.

If the SSSS is the reason we run a simplified cartoon of the world in our conscious minds, that may explain why we have a subjective experience of consciousness, but it still doesn’t explain why it feels exactly the way it does. The exact feel is a consequence of how data flows into our minds. To be effective, the conscious mind must not overlook any important source of information when making a decision. For example, any of our senses might provide key information at any time. For this reason, this information is fed to the conscious mind through sensory data channels called qualia, and each quale (kwol-ee, the singular) is a sensory quality, like redness, loudness or softness. Some even blend to create, for example, the sensation of a range of colors. The channels provide a streaming experience much like a movie. While the SSSS focuses on just the aspects most relevant to making decisions, it has an awareness of all the channels simultaneously. So it is capable of processing inputs in parallel even though it must narrow its outputs to a single stream of selected steps.

But why do data channels “feel” like something? First, we have to keep in mind that as substantial as our qualia feel, it is all in our heads, meaning that it is ultimately just information and not a physical quality. There is no magic in the brain, just information processing. A lot of information processing goes into creating the conscious theater of mind; it is no coincidence that it seems beautiful to us. Millions of years went into tailoring our conscious experience to allow all the qualia to be distinct from each other and to inform the reasoning process in the most effective way. Any alteration to that feel would affect our ability to make decisions. How should hot and cold feel? It doesn’t really matter what they feel like so long as you can tell them apart. Surprisingly, out of context, people can confuse hot with cold, because they use the same quale channel and we use them in a highly contextual way. Specifically, If you are cold, warmth should feel good, and if you are hot, coolness should feel good. And lo and behold, they do feel that way. Much of the rich character we associate with qualia comes not from the raw sensory feel itself but from the contextual associations we develop from genetic predispositions and years of experience. So red and loud will seem a bit scarier and alarming than blue or quiet, and soft will seem more soothing than rough. Ultimately, that qualia feel so rich and fit together seamlessly into a smooth movie-like experience proves that extensive parallel subconscious computational support goes into creating them.

Beyond sensory qualia, data channels carry other streams of information from subconscious processing into our conscious awareness. These streams enhance the conscious experience with emotion, recognition, and language. The subconscious mind evaluates situations, and if it finds cause for sadness (or other emotional content), then it informs the conscious mind, which then feels that way. We feel emotional qualia as distinctly as sensory qualia, and the base emotions seem to have distinct channels as we can feel multiple emotions at once. Recognition is a subconscious process that scans our memory matching everything we see and experience to our store of objects and experiences (concepts). It provides us with a live streaming data lookup service that tells us what we are looking at along with many related details, all automatically. We think of language as a conscious process, but only a small part is conscious. A processing engine hidden to our conscious minds learns the rules of our mother tongue (and others if we teach it), and it can generate words and sentences that line up with the propositions flowing through the SSSS, or parse language we hear or read into such propositions. Language processing is a kind of specialized recognition channel that connects symbols to meanings. The goal is for the conscious mind to have a simple but thorough awareness of the world, so everything not directly relevant to conscious decision making is processed subconsciously so as not to be a distraction. Desires don’t have their own qualia but instead add color to sensory and emotional qualia. Computationally this means additional information about prioritization comes through the qualia data channels. Desires come through recognition data channels (memory) as beliefs. Beliefs are desires we have committed to memory in the sense that we have computed our level of desire and now remember it. As noted above, recall that desires and beliefs are the only factors that influence how we prioritize our actions.

While we are born with no memories, and consequently all recognition and language are learned, we are so strongly inclined to learn to use our subconscious skills that all humans raised in normal environments will learn how without any overt training. We thus learn to recognize objects and experience appropriate emotions in context whether we like it or not. Similarly, we can’t suppress our ability to understand language. Interestingly, lack of conscious control over our emotions has been theorized to help others “see” our true feelings, which greatly facilitates their ability to trust us and work for both parties’ best interests. Other subconscious skills also include facility with physics, psychology, face recognition and more, which flow into our consciousness intuitively. We are innately predisposed to learn these skills and once trained we use them miraculously without conscious thought. The net result of all these subconsciously produced data channels is that the conscious mind is fed an artificial but very informative and largely predigested movie of the world, so much so that our conscious minds can, if they like, just drift on autopilot enjoying the show with little or no effort.

Lots of information flows into the conscious mind on all these data channels. It is still too much for the SSSS to process using modeling and logical propositions. So while we have a conscious awareness of all of it, attention is a specialized ability to focus on just the items relevant to the decision-making process. Computationally, what attention does is fill the local variable slots of the SSSS process with the most relevant items from the many data channels flowing into the conscious mind. So just as you can only read words at the focal point of your vision, you can only do logic on items under conscious attention, though you retain awareness of all the data channels analogously to peripheral vision. Further, since those items must be representational, data from sensory or emotional qualia must first be processed into representations through recognition channels. We can shift focus to senses and emotions, e.g. to consciously control breathing, blinking, or laughing, through representations as well. It is similar for learned behaviors. We can not only walk and chew gum at the same time, we can also carry on a conversation that engages most of our attention. Same for when we are tying our shoes or driving. But to stay on the lookout for novel situations, we retain conscious awareness of them and can bring them to attention if needed. Conscious focus is how we flexibly handle the most relevant factors moment to moment. Deciding what to focus on is a complex mental task itself that is handled almost entirely subconsciously.

The loss of smell in humans probably follows from the value in maintaining a simple logical model. Humans, and to a lesser degree other primates, have lost much of their ability to smell, which has probably been offset by improvements in vision, specifically in color and depth. That primates benefit more from better vision makes sense, but why did we lose so much variety and depth from smell perception? Disuse alone seems unlikely to explain so much loss considering rarely-used senses are still occasionally useful. The more likely explanation is that the sense of smell was a troublesome distraction from vision. That is, when forced to rely on vision primates did better than they would with both vision and smell. This can be explained by analogy to blind people, who develop other senses more keenly to compensate. Those forced to develop more keen visual senses could use them more effectively in many ways than those who trusted smell, which may turn out not to deliver as much benefit for primates, and especially humans. If you consider how much value we get from vision compared to smell, this seems like a good trade-off.

To summarize what I have said so far, the conscious mind has a broad subrational awareness of much sensory, emotional and recognition data. It can use intuition, learned behavior, and many subconscious skills but does so with conscious awareness and supervision. To consciously reason, the SSSS processes representations created by generalizing that data. The SSSS only reasons with propositions built on representations under conscious attention, i.e. those that are relevant. Innate desires are used to prioritize decisions, that is, they lead us to do things we want to do.

We know we are smarter than animals, but what exactly do we do that they can’t? Use of tools, language (and symbols in general), and self-awareness seem more like consequences of greater intelligence than its cause. The key underlying mental capacity humans have that other animals lack is directed abstract thinking. Only humans have the facility and penchant for connecting thoughts together in arbitrarily complex and generalized ways. In a sense, all other animals are trapped in the here and now; their reasoning capacities are limited to the problems at hand. They can reason, focus, imitate, wonder, remember, and dream but they can’t daydream, which is to say they can’t chain thoughts together at will just to see what might happen. If you think about it, it is a risky evolutionary strategy as daydreamers might just starve. But our instinctual drives have kept up with intelligence to motivate us to meet evolutionary requirements. Steven Pinker believes metaphors are a consequence of the evolutionary step that gave humans directed abstract thinking:

When given an opportunity to reach for a piece of food behind a window using objects set in front of them, the monkeys go for the sturdy hooks and canes, avoiding similar ones that are cut in two or made of string of paste, and not wasting their time if an obstruction or narrow opening would get in the way. Now imagine an evolutionary step that allowed the neural programs that carry out such reasoning to cut themselves loose from actual hunks of matter and work on symbols that can stand for just about anything. The cognitive machinery that computes relations among things, places, and causes could then be co-opted for abstract ideas. The ancestry of abstract thinking would be visible in concrete metaphors, a kind of cognitive vestige.

…Human intelligence would be a product of metaphor and combinatorics. Metaphor allows the mind to use a few basic ideas — substance, location, force, goal — to understand more abstract domains. Combinatorics allows a finite set of simple ideas to give rise to an infinite set of complex ones.1

Pinker believes the “stuff of thought” is sub-linguistic, and is only translated to/from a natural language for communication with oneself or others. That is, he does not hold that we “think” in language. But we can’t discuss thinking without distinguishing conscious and subconscious thought. Consciously, we only have access to the customized data channels our subconscious provides us to give us an efficient, logical interface to the world. In humans, a language data channel gives us conscious access to a subconscious ability to form or decompose linguistic representations of ideas. I agree with Pinker that the SSSS does not require language to reason, but language is a critical data channel integrally involved with advanced reasoning, i.e. directed abstract thinking. The SSSS processes many lines of thought across many models with many possible interpretations, which we can think of as being done in parallel (i.e. within conscious awareness) or in rotation (i.e. under conscious focus). But because language reduces thought to a single stream it provides a very useful way to simplify the logical processing of the SSSS down to one stream that can be put to action or used to communicate with oneself or others. Also, language is a memory aid and helps us construct more complex chains of abstract thought than could easily be managed without it, in much the same way writing amps up our ability to build longer and clearer arguments than can be sustained verbally. So the linguistic work of SSSS, i.e. conscious thought, works exclusively with natural language, but most of the real work (computationally speaking) of language is done subconsciously by processes that map meaning to words and words to meaning. Pinker somewhat generically calls the subconscious level of thinking “mentalese”, but this word is very misleading because it suggests a linguistic layer underlies reasoning when it doesn’t. Language processing is done by a specialized language center that feeds both natural language and its meaning to/from our conscious minds (the SSSS). And this center uses processing algorithms that can only process languages that obey the Universal Grammar (UG) Noam Chomsky described. But the language center does no reasoning; reasoning is a function of the SSSS, for which natural language is a tool that helps broker meanings.

So let’s consider metaphor again. The SSSS reasons with propositions built on representations that are themselves ultimately generalizations about the world. Metaphor is a generalized use of generalizations. It is a powerful tool of inductive reasoning in its own right that can help explain causation by analogy independent of its use in language. But language does make extensive use of metaphorical words and idioms as a tool of reasoning because a metaphor implies that explanations about the source will apply to the target. And more broadly, metaphors, like all ideas, are relational, defined in terms of each other, and ultimately joined to physical phenomena to anchor our sense of meaning. I agree with Pinker that metaphor provides a useful way to create words and idioms for ideas new to language and that these metaphors become partly or wholly vestigial when words or idioms are understood independent of their metaphorical origin. The words manipulate and handle derive from the skillful use of hands and yet are also applied to skillful use of the mind, and many mental words have physical origins and often retain their physical meanings, but we use them mentally without thinking of the physical meaning. But metaphorical reasoning is also well supported by language just because it is a powerful explanatory device.

An important consequence of directed abstract thinking and language is that humans have a vastly larger inventory of representations or concepts with which they can reason than other animals. We have distinct words for a small fraction of these, and most words are overloaded generalizations that we apply to a range of concepts we can actually distinguish more finely. We distinguish many kinds of parts and objects in our natural and artificial environments and many kinds of abstract concepts like health, money, self, and pomposity.

But what about language, tool use, and self-reflection? No one could successfully argue that chimps could do this as well as us if only they had generalized abstract thought. While generalized abstract thought is the underlying breakthrough that opened the floodgates of intelligence, it has co-evolved with language, manipulating hands and the wherewithal to use them, and a strong sense of self. Many genetic changes now separate our intellectual reach from our nearest relatives. Any animal can generalize from a strategy that has worked before to apply it again in similar circumstances, but only humans can reason at will about anything to proactively solve problems. Language magically connects words and grammar to meanings for us through subconscious support, but we are most familiar with how we consciously use it to represent and manipulate ideas symbolically. We can’t communicate most abstract ideas without using language, but even to develop ideas in our own mind though a chain of reasoning language is invaluable. Though our genetic separation from chimps is relatively small and recent, the human mind takes a second order qualitative leap into the ideal world that gives us unlimited access to ideas in principle because all ideas are relationships.

  1. Steven Pinker, 2007, The Stuff of Thought, p242-243

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