A little bit of naturalist apologia

We live in a world where most natural phenomena, from the micro level of atoms, cells and molecules up to the macro level of galaxies and the universe itself, seem to be describable and explicable in physical terms. Physicalism (I mean by this term the metaphysical position that only the physical universe exists) is, as I said, by no means triumphant (and it is a reasonable point that contemporary physics itself presents us with a still-mysterious and newly-strange picture of the universe). There are ongoing popular metaphysical arguments about evolutionary biology and about cosmology, for example. But it is a striking fact about contemporary culture that psychology (and by extension the behavioral and social disciplines) are still not considered to be integrated into our otherwise generally physicalist metaphysics. Put another way, while many people today have firmly internalized physicalist intuitions about organic life, say, or about distant celestial objects, physicalist theories of mind still meet with resistance today, even among secular people who have broadly physicalist attitudes.

I’m not someone motivated mostly by ideology. I’ve always been impressed by Socrates’ description (in the Theatetus) of the search for knowledge as the activity of becoming aware of what it is that one truly believes, and then stating that belief, above all to oneself, as clearly and courageously as possible (in fact Socrates is claiming, contra his relativist antagonists, that this is the essential, unavoidable human activity). I’ve had the salutary experience of changing my mind and reversing myself several times during my relationship with philosophy of mind. Now I just want to develop the soundest view of the matter that I can, as one climbs a mountain. One of the worst faults a philosopher can have is the tendency to magical thinking: trying to make a brief for what one wants to be true.

However another couple of paragraphs of self-explanation are warranted. I know this because I have spent the past ten years or so teaching the philosophy of mind to undergraduates at two large state universities. Inevitably this involves, among other things, leading a lay audience to discuss, usually for the first time, the topic of naturalism with regard to human nature and to the mind. Of course there are people who arrive in the classroom already thoroughly naturalistic. But consistently there are people who struggle with this topic for deeper, cultural reasons. Although this discussion is rarely included in books on philosophy of mind, I have found that it is best to present some apologia at the beginning for students who may have some preconceptions that can turn them off, as well as to reassure them that I too think that these are legitimate concerns that can be discussed if they wish.

OK, so here’s an ideological argument: Humans are depressingly alienated from nature. Our relationship with the rest of the biota on this planet is not a good one. Urgent action is necessary to stem climate change, species extinction and other environmental problems that pose grave threats. However we also need longer-term cultural evolution, a change in our attitude towards our relationship with nature, and this change is effected to some extent by cultural workers such as artists, philosophers and writers.

It is my opinion that human exceptionalism, and a lot of bad metaphysics down a lot of centuries that came with it, is one root of our dysfunctional relationship with nature. I think that naturalism about psychology is the most progressive view. I think that naturalism is also the most spiritual view. And it is the healthiest view of human nature. I may be all wrong on all of that. But the reader ought to understand that I concede no quarter of the argument between physicalism about the mind and its alternatives, including discussions in terms of enlightenment, ethics, freedom, spirituality and so forth. Those discussions, however, will form little or no part of this book.

A programmatic point that will be discussed, though, is the importance of clearing up some of the logical and linguistic problems that we continue to have with our concept of “mind” in order to make progress in experimental science. Theory can have a good deal to say about the development of experimental protocols, and good theory will make these implications clear.

Metaphysics and the philosophy of mind

This is a book about the metaphysics of the mind/body problem. Metaphysics (or “ontology”) is the study of what exists (Aristotle called it the study of “being”). To many people today metaphysics seems anachronistic. Haven’t we settled the issue of what exists, they might ask, in favor of the physical universe? And isn’t natural science the way we produce knowledge about this universe? How could more work in metaphysics possibly generate any persuasive arguments, if “metaphysics” is not simply “physics”? Arguments about the relationship between the mind and the body that aren’t grounded in empirical research of some sort can’t hope to be legitimate in a world awash in data from experimental psychology, neuroscience, computer science, evolutionary biology, linguistics and the myriad of interdisciplinary areas of research that today we call “cognitive studies.” Isn’t a metaphysician a mere poet of speculation? Diverting at best, but such a person has no hope of producing useful knowledge. That, anyway, is often the initial reaction one meets with the topic of the metaphysics of the mind/body problem. I will respond to this initial “meta”-challenge in two ways.

First, I completely embrace the spirit, and much of the letter, of this initial objection. I too take it as axiomatic that what exists is the physical universe (by “physical” I mean the universe of matter and energy, or maybe matter/energy; I don’t pretend to be sophisticated about theoretical physics). I don’t think that humans are composed of physical bodies and non-physical souls, like a traditional mind/body dualist. I think that humans are physical through and through, animals that evolved here on earth through a long process of evolution the contingencies of which were, and continue to be, bounded by the constants of biology, chemistry, and physics. I don’t expect to discover that humans are angels, or that the physical universe is an illusion and humans are non-physical spirits, or anything like that.

The universe is as magical, mysterious and mystical as it may be; I don’t know anything about the ultimate composition or nature of the universe. I have no interest in making a brief for reduction, as if natural science can address every one of our wonders, or even potentially could. I don’t even know what we’re talking about when we use that kind of language. My claim is much humbler: whatever nature in general is like, humans are like that. Humans are not miracles, if a “miracle” is defined as an exception to the laws of nature. Call me an “anti-humanist.” I hold the anti-humanist view simply because I know of no reason to think that humans are miracles; I stress it because a deeply internalized assumption of human exceptionalism continues to be a barrier to progress across the whole range of the behavioral and cognitive sciences.

Which brings me to the second response to the objection that metaphysics is anachronistic: it is certainly not true that the contemporary society of educated people embraces anti-humanism as I just defined it. A great many college students, most people walking down the street and the overwhelming majority of the world’s population today continue to think that the mind is something distinct from the body or, at least, that mental phenomena cannot be adequately described and explained in wholly physical terms. This conviction has various sources that range from traditional, usually religion-based beliefs about souls, afterlives and so forth to more modern notions, such as the view that a naturalistic view of human nature is perniciously reductive and to be resisted by the liberal-minded, or perhaps that science itself is nothing more than a socially-constructed “conceptual scheme” with no particular claim to legitimacy, and so on. For another thing, very sophisticated versions of human exceptionalism exist in the academy today (for example among some linguists), such that it is by no means established conventional wisdom that physical science subsumes psychology by metaphysical axiom.

Metaphysics is not something that is replaced by physics. Physicalism is a particular metaphysical position. Everyone has metaphysical assumptions, articulated or not, whether they want to or not, and they always will. The person who chafes at the idea that there is still a need for explicitly metaphysical discussion is claiming that our shared metaphysical assumptions are currently stable, not that “there is no such thing as metaphysics,” although they may unreflectively put it that way. It’s true that physicalism is currently the ruling metaphysical paradigm among cognitive scientists, psychologists, philosophers and so on, and I too labor within this paradigm, albeit with some important qualifications that are discussed in the second part of Chapter Two.

Elan Mental

The claim that there is something (the quality of phenomenal experience) that cannot be explained by physical science is strictly analogous to the 19th century “vitalist” claim that the property of being alive could not be explained by physical science (the phrase “élan vital” was actually coined later, in 1907, by Henri Bergson in his book Creative Evolution). Consider all of the physical facts about physical states and processes in the body, the vitalist argued: singularly or together none of these facts entail that the body be alive.

This “hard problem” was never “solved.” It simply faded away as organic chemistry and physiology steadily explicated the physical mechanisms and processes occurring in various parts of cells, and in the various organs of the body. This took some time, well into the 20th century, but by the 1940s, anyway, it was no longer credible to claim that “life” was something that might not be present when these mechanisms and processes of organic chemistry were present, or might be present in their absence. “Life” will always be an ambiguous concept to some extent (there is ongoing debate as to whether viruses are living, for example), because it is an emergent property, but its physical nature is no longer seriously challenged. The concept of “consciousness” is now undergoing the same evolutionary process – not a similar process, the very same process.

This analogy has been prominently rehearsed by Patricia Churchland and by John Searle, among others. I will consider Searle’s version a little more closely by way of setting up the last chapter, where I will discuss the relationship between intentionality and consciousness. Searle makes an analogy between the solidity of a table and the consciousness of a brain: the table’s solidity is a macro-property that emerges from the micro-properties of the wood molecules (which are lattice-like). Consciousness, he suggests, is a macro-property that emerges from the micro-properties of neurons (although he doesn’t claim to know which micro-properties or why).

There are two problems with Searle’s analogy. First, in the case of the wood molecule and the table, they share the same property in the first place: the lattice-like structure of the wood molecule, like a folded piece of paper, just is solid (can bear weight by virtue of its structure). So solidity is not an “emergent macro-property,” solidity is already a property of the “micro” ingredients. If the question is “How can physical objects support weight?” then appeal to the weight-bearing nature of the wood molecule only pushes this question back a step. This problem with the analogy is irremediable: if the argument is that brains are conscious because neurons are conscious we have once again committed the hard-to-avoid error of including something mental in our purported recipe for the mental. If not, then the analogy does not go through: the wood molecules and the table share a property in common, so we do not have an actual example of a macro-property emerging from a micro-property (that is not to say that we couldn’t find such an example, only that this one isn’t it).

The second problem is more serious and to the point of the present discussion. Psychological predicates, as I argued at length in Chapter Two, are not predicated of brains or nervous systems but of whole persons. This goes for consciousness every bit as much as it does for intentionality. Brains no more feel or sense things than they think about or imagine things. Persons think and feel. Asserting this does not exclude me from the club of materialists in any way.

The crucial difference between intentionality and consciousness is that while intentional states are supervenient and therefore unexplainable through reductive materialism, phenomenal states are not supervenient and so a legitimate answer to the question “Why does it feel like that?” is “Because it is that specific physical body interacting with that specific physical feature of the environment (chocolate molecule, blue-reflecting surface, soft pillow etc)” – strict reductive materialism. We can say this, I think, even if we accept the argument that the question “Why does it feel like that?” is itself in a sense illegitimate since there is no way to fill in the sense of “that,” as Hume, Wittgenstein and the Buddhists argue. The basic insight is that having these conscious experiences is indistinguishable from having this physical body in this physical world.

There is only one sense in which we can coherently say that our own phenomenal experiences are in any way similar to those of other conscious beings, such that we can grasp a link between intentionality (universal among all intelligent beings) and consciousness (unique to each conscious being). In this book I have emphasized the distinction between intentionality and consciousness. The last chapter will explore the connection between them.

Hyper-chauvinistic type-to-type reductive materialism

OK, it’s not really hyper-chauvinistic type-to-type reductive materialism, because there isn’t anything to “reduce,” if the above arguments are persuasive. But the fact is that so far as qualitative experience is concerned, yours is what it is because you have the body that you have. “Experiencing” is just identical to living in a body like that.

A crucial difference between intentional states and phenomenal states is that phenomenal states are not picked out operationally, while intentional states are, even though the criteria for use of phenomenal predicates is operational just as they are for the use of intentional predicates. This is because phenomenal experience is outside of the reach of language altogether: precisely because it is unique to oneself and thus incommunicable to another. This is a difference between bodies.

Saul Kripke, much of whose work was inspired by Wittgenstein, argued that reduction was impossible on linguistic grounds. A phenomenal word like “pain” could never be defined as, say, “C-fibers firing” because the word “pain” referred to the feeling of pain (that phenomenal experience), and, Kripke argued, one can imagine being in pain without one’s C-fibers firing (or without having C-fibers at all) and that one’s C-fibers might be firing (or what have you) without one feeling pain. Of course Kripke’s point is about all phenomenal language but, as we have seen, there is no coherent way to separate “experience of the world” from “the world.”

Kripke’s claim amounts to saying that one can imagine experiencing this world without this world (which includes one’s body), or that this world (including this body) could exist without these experiences. I take Hume’s point that these sorts of claims about what can be conceived or imagined are meaningless, because phenomenal experience of the world and the world itself cannot be metaphysically distinguished from each other.

However this does not mean that “pain” might be defined as C-fibers firing: it could not. Use of the word “pain” will be determined operationally (as David Lewis insisted) as the use of all words is determined operationally. Constructions such as “pain-for-me” have no functional role in communication, but one’s (actual) pain can be mentioned even if there is no use for a term that designates it: it is no less real for being inexpressible. Meanwhile Kripke is not entitled to the claim that one’s body (one’s C-fibers firing) is causing one to have a sensation of pain that is distinct from its cause. Such a claim is irremediably dualist: one’s body is not the cause of one’s phenomenal experience. One just is one’s C-fibers firing etc.

Better, then, to drop the “reductive.” But “type-to-type” is also a dubious phrase. Unlike in the case of intentional states, there is no distinction between types and tokens when we are referring to conscious experience: each body is to some extent unique, and consciousness (unlike intentionality) is not supervenient. And the suffix “hyper” is perhaps a bit of rhetoric on my part. Better, perhaps, to call our theory of phenomenal mind simply “chauvinistic materialism,” if the need is still felt for a “theory” to account for a pseudoproblem.

This is no problem for science; since science, understood as a cultural artifact, is limited to the intersubjective, and phenomenal experience is wholly subjective (that’s why it’s a little silly to say that we have a “theory” here at all). Thus we can contemplate the resolution of the so-called “hard” problem of consciousness.

Phenomenal states are not supervenient

Intentional states are multiply realizable, and functionalism was motivated by this fact. The supervenient nature of intentional states constitutes a real block to reductive materialism for intentionality. However intentional states can be individuated operationally. The intuition that the psychological description “He likes chocolate” involves a reference to the subject’s qualitative experience of tasting chocolate is wrong (or, we can mention the qualitative experience but we cannot actually convey it). In the case of the Martians we might not know if they even “taste” things at all; nonetheless we might come to know that they like chocolate.

A consequence of the necessarily operational basis of intentional descriptions is that, to use an example made famous by Daniel Dennett (although I don’t know that Dennett would agree with my line here), a lowly thermostat is a kind of intentional system: we can determine when it thinks that the room is too cold, just right or too hot. The intuition that this can’t be, that a thermostat is clearly not a mind, is a consequence of internalizing the traditional homogeneous concept of “mind” (because the thermostat has no Nagelian experience), aggravated by the prevailing dogma that thinking necessarily involves representations. When we disambiguate “mind” and see that intentionality is something altogether different than consciousness there is no denying that the thermostat is, in fact, an intentional being; nor does that fact in any way compromise our philosophical use of the term “intentionality.”

The qualities of experience, on the other hand, are not supervenient. It is plainly true that humans, dolphins, probable intelligent extraterrestrials and possible intelligent artifacts, among an indefinitely large set of other beings, can all believe that the chocolate is in the box, desire the chocolate and so forth. But there is no reason whatever to think that chocolate tastes like that (the way it tastes to me, say) for all of the members of the set: there isn’t even any reason to think that all of the members of the set of chocolate-desirers taste anything at all.

Ironically what this amounts to is that intentional properties are more ontologically mysterious, not less, than phenomenal properties. Consciousness has been called the “hard problem,” but in fact the right metaphysical account of consciousness is, relative to that of intentionality, positively straightforward.