Daniel C. Dennett

(1942 - 2024)

A family of compelling intuitions work to keep "the problem of consciousness" systematically insoluble, and David Rosenthal, in a series of papers including the one under discussion, has been resolutely driving these intuitions apart, exposing them individually to the light, and proposing alternatives. In this instance the intuition that has seemed sacrosanct, but falls to his analysis, is the intuition that "sensory quality" and consciousness are necessarily united: that, for instance, there could not be unconscious pains, or unconscious subjective shades of blue, or unconscious aromas of freshly roasted coffee beans. The particular airborne polymers that are the vehicles of freshly roasted coffee beans could exist, of course, in the absence of any observer, and hence of any consciousness, but the sensory quality of that aroma requires--according to well-entrenched intuition--not only an observer but a conscious observer. Such properties have no esse except as percipi.

Two books published within months of each other, each critical of the reigning family of working assumptions known as cognitive science, each calling for a more biological vision of the mind and even sharing a slogan: we must see the mind as "embodied". Is this merely a striking coincidence or perhaps a case of convergent evolution of scientific ideas? There are further striking similarities. Francisco Varela, the principle author of The Embodied Mind, is an immunologist-turned-neuroscientist, and so is Gerald Edelman, author of Bright Air, Brilliant Fire. Both books call for a biological counter-revolution to succeed the cognitive revolution, but neither are attracted to the even more radically revolutionary "quantum gravity" speculations of Roger Penrose.

One of the things you learn if you read books and articles in (or about) cognitive science is that the brain does a lot of "filling in"--not filling in, but "filling in"--in scare quotes. My claim today will be that this way of talking is not a safe bit of shorthand, or an innocent bit of temporizing, but a source of deep confusion and error. The phenomena described in terms of "filling in" are real, surprising, and theoretically important, but it is a mistake to conceive of them as instances of something being filled in, for that vivid phrase always suggests too much--sometimes a little too much, but often a lot too much. Here are some examples (my boldface throughout)

Once upon a time, there were two large black boxes, A and B, connected by a long insulated copper wire. On box A there were two buttons, marked *a* and *b*, and on box B there were three lights, red, green, and amber. Scientists studying the behavior of the boxes had observed that whenever you pushed the *a* button on box A, the red light flashed briefly on box B, and whenever you pushed the *b* button on box A, the green light flashed briefly. The amber light never seemed to flash. They performed a few billion trials, under a very wide variety of conditions, and found no exceptions. There seemed to them to be a causal regularity, which they conveniently summarized thus.

As cognitive science, including especially cognitive neuroscience, closes in on the first realistic models of the human mind, philosophical puzzles and problems that have been conveniently postponed or ignored for generations are beginning to haunt the efforts of the scientists, confounding their vision and leading them down hopeless paths of theory. I will illustrate this claim with a brief look at several temporal phenomena which appear anomalous only because of a cognitive illusion: an illusion about the point of view of the observerix. Since there is no point in the brain where "it all comes together," several compelling oversimplifications of traditional theorizing must be abandoned.

What is a self? I will try to answer this question by developing an analogy with something much simpler, something which is nowhere near as puzzling as a self, but has some properties in common with selves. What I have in mind is the center of gravity of an object. This is a well-behaved concept in Newtonian physics. But a center of gravity is not an atom or a subatomic particle or any other physical item in the world. It has no mass; it has no color; it has no physical properties at all, except for spatio-temporal location. It is a fine example of what Hans Reichenbach would call an abstractum. It is a purely abstract object. It is, if you like, a theorist's fiction. It is not one of the real things in the universe in addition to the atoms. But it is a fiction that has nicely defined, well delineated and well behaved role within physics.

Cognitive science, as an interdisciplinary school of thought, may have recently moved beyond the bandwagon stage onto the throne of orthodoxy, but it does not make a favorable first impression on many people. Familiar reactions on first encounters range from revulsion to condescending dismissal--very few faces in the crowd light up with the sense of "Aha! So that's how the mind works! Of course!" Cognitive science leaves something out, it seems; moreover, what it apparently leaves out is important, even precious. Boiled down to its essence, cognitive science proclaims that in one way or another our minds are computers, and this seems so mechanistic, reductionistic, intellectualistic, dry, philistine, unbiological. It leaves out emotion, or what philosophers call qualia, or value, or mattering, or... the soul. It doesn't explain what minds are so much as attempt to explain minds away.

What I find particularly valuable in the juxtaposition of these three essays on my book is the triangulation made possible by their different versions of much the same story. I present my view as a product of cognitive science, but all three express worries that it may involve some sort of ominous backsliding towards the evils of behaviorism. I agree with Baars and McGovern when they suggest that philosophy has had some baleful influences on psychology during this century. Logical positivism at its best was full of subtle softenings, but behaviorist psychologists bought the tabloid version, and sold it to their students in large quantities. George Miller's account of those dreary days is not an exaggeration, and the effects still linger in some quarters. (Philosophers are often amused--but they should really be disconcerted--to note that the only living, preaching logical positivists today are to be found in psychology departments.).

Sydney Shoemaker notes that my "avoidance of the standard philosophical terminology for discussing such matters" often creates problems for me; philosophers have a hard time figuring out what I am saying and what I am denying. My refusal to play ball with my colleagues is deliberate, of course, since I view the standard philosophical terminology as worse than useless--a major obstacle to progress since it consists of so many errors trapped in the seductively lucid amber of tradition: "obvious truths" that are simply false, broken-backed distinctions, and other cognitive illusions. I want to shift the perspective of philosophy of mind, and for that task using the standard terminology would be counterproductive. Fortunately, the inevitable communication-difficulties my policy provokes are forced into the open by occasions such as this constructive confrontation, permitting me to clarify my shocking message. I am grateful to Shoemaker, and to Michael Tye, Frank Jackson and David Rosenthal, for their vigorous and sympathetic reactions to my book.

Reading these essays has shown me a great deal, both about the substantive issues I have dealt with and about how to do philosophy. On the former front, they show that I have missed some points and overstated others, and sometimes just been unable to penetrate the fog. On the latter front, they show how hard it is to write philosophy that works--and this is the point that stands out for me as I reflect on these rich and varied essays. Philosophical books and articles routinely fail to achieve their manifest goal of persuading their intended audiences of their main points. Does this make philosophy any worse off than other writing endeavors? Most published novels are failures of one sort or another, and the press has reported a recent study (whose methodology I wonder about) that concludes that the median number of readers of any paper published in a psychology journal is zero. But it seems to me that philosophy displays a particularly feckless record, with such a huge gap between authorial pretense and effect achieved that it is perhaps more comic than pathetic. In one weak moment I found myself thinking that perhaps some of our French colleagues have the right idea: deliberate obscurantism and the striking of stylized poses--since the goal of persuading by clear, precise analysis and argument is so manifestly beyond us. But that worldly weariness passed, I'm happy to say, and my cock-eyed American optimism returned. My ambition continues to be to change people's minds, and not just to win people over to my way of doing philosophy, as Bo Dahlbom suggests. But I admit that it is harder than I had thought. It's hard enough to get a good idea, but sometimes it's even harder, apparently, to get others to see what the idea is, and why it's good.

No response that was not as long and intricate as the two commentaries combined could do justice to their details, so what follows will satisfy nobody, myself included. I will concentrate on one issue discussed by both commentators: the relationship between evolution and teleological (or intentional) explanation. My response, in its brevity, may have just one virtue: it will confirm some of the hunches (or should I say suspicions) that these and other writers have entertained about my views. For more closely argued defenses of my points, see Dennett 1990a,b,c; 1991a,b.

Everyone agrees that consciousness is a very special phenomenon, unique in several ways, but there is scant agreement on just how special it is, and whether or not an explanation of it can be accommodated within normal science. John Searle's view, defended with passion in this book, is highly idiosyncratic: what is special about consciousness is its "subjective ontology," but normal science can accommodate subjective ontology alongside (not within) its otherwise objective ontology. Once we clear away some widespread confusions about what science requires, and dismiss the misbegotten field of cognitive science that has been engendered by those confusions, the subjective ontology of the mind, he claims, will lose its aura of unacceptable mystery.

In a survey of issues in philosophy of mind some years ago, I observed that "it is widely granted these days that dualism is not a serious view to contend with, but rather a cliff over which to push one's opponents." (Dennett, 1978, p.252) That was true enough, and I for one certainly didn't deplore the fact, but this rich array of essays tackling my book amply demonstrates that a cliff examined with care is better than a cliff ignored. And, as I have noted in my discussion of the blind spot and other gaps, you really can't perceive an edge unless you represent both sides of it. So one of the virtues of this gathering of essays is that it permits both friend and foe alike to take a good hard look at dualism, as represented by those who are tempted by it, those who can imagine no alternative to it, and those who, like me, still find it to be--in a word--hopeless.

One puzzling feature of the response to "Evolution, Error, and Intentionality" has contributed to the direction of my current research on evolution. I was initially dumfounded by the willingness of philosophers simply to dismiss or ignore--as too radical to be taken seriously, apparently--my suggestion that we are survival machines for our genes, as Dawkins has put it. This surprised me, for in point of fact the biology on which I based my philosophical extrapolations is not even controversial. It is uncontested that human bodies, like the bodies of all other creatures, are products of a design process that tracks, in the first instance, the "interests" of the genes whose phenotypic expressions those bodies are. There are substantive controversies about the importance of this fact, but not the fact itself.

Arguments about whether a robot could ever be conscious have been conducted up to now in the factually impoverished arena of what is possible "in principle." A team at MIT of which I am a part is now embarking on a longterm project to design and build a humanoid robot, Cog, whose cognitive talents will include speech, eye-coordinated manipulation of objects, and a host of self-protective, self-regulatory and self-exploring activities. The aim of the project is not to make a conscious robot, but to make a robot that can interact with human beings in a robust and versatile manner in real time, take care of itself, and tell its designers things about itself that would otherwise be extremely difficult if not impossible to determine by examination. Many of the details of Cog's "neural" organization will parallel what is known (or presumed known) about their counterparts in the human brain, but the intended realism of Cog as a model is relatively coarse-grained, varying opportunistically as a function of what we think we know, what we think we can build, and what we think doesn't matter. Much of what we think will of course prove to be mistaken; that is one advantage of real experiments over thought experiments.

In my opinion, the two main topics in the philosophy of mind are content and consciousness. As the title of my first book, _Content and Consciousness_ (1969) suggested, that is the order in which they must be addressed: first, a theory of content or intentionality--a phenomenon more fundamental than consciousness--and then, building on that foundation, a theory of consciousness. Over the years I have found myself recapitulating this basic structure twice, partly in order to respond to various philosophical objections, but more importantly, because my research on foundational issues in cognitive science led me into different aspects of the problems. The articles in the first half of.