Daniel C. Dennett

(1942 - 2024)

Philosophical controversy about the mind has flourished in the thin air of our ignorance about the brain. The humble toad, it now seems, may provide our first instance of a creature whose whole brain is within the reach of our scientific understanding. What will happen to the traditional philosophical issues as our theoretical and factual ignorance recedes? Discussion of the issues explored in the target article is, as Ewert says, "often too theoretical, sometimes philosophical and even [as if that weren't bad enough?--DCD] emotion-laden." The research reported by Ewert has interesting philosophical implications, as he probably recognizes, but he wisely leaves the philosophy to the philosophers. Being one, I would like to draw some of the conclusions he eschews.

In "Propositions about Images" Philip Cam accurately analyzes and criticizes the grounds I gave, in the works he cites, for my denial that we have privileged access (of any sort) to anything deserving to be called a mental image. He shows that I did not deal properly with the question of how I would interpret the ostensive force of "this" and "that" in an introspective judgment of the sort: "Now it looks like this and now it looks like that." What can one be ostending or referring to in such a case, if not to an image (or some feature of an image)?

The intentional stance is the strategy of prediction and explanation that attributes beliefs, desires, and other states to systems and predicts future behavior from what it would be rational for an agent to do, given those beliefs and desires. Any system whose performance can be thus predicted and explained is an intentional system, whatever its innards. The strategy of treating parts of the world as intentional systems is the foundation of but is also exploited in artificial intelligence and cognitive science more generally, as well as in evolutionary theory. An analysis of the role of the intentional stance and its presuppositions supports a naturalistic theory of mental states and events, their content or intentionality, and the relation between levels of explanation and neurophysiological or mechanistic levels of explanation. As such, the analysis of the intentional stance grounds a theory of the mind and its relation to the body.

In Word and Object, Quine acknowledged the "practical indispensability" in daily life of the intentional idioms of belief and desire but disparaged such talk as an "essentially dramatic idiom" rather than something from which real science could be made in any straightforward way.Endnote 1 Many who agree on little else have agreed with Quine about this, and have gone on to suggest one or another indirect way for science to accommodate folk psychology: Sellars, Davidson, Putnam, Rorty, Stich, the Churchlands, Schiffer and myself, to name a few. This fainthearted consensus is all wrong, according to Fodor, whose new book is a vigorous--even frantic--defense of what he calls Intentional Realism: beliefs and desires are real, causally involved, determinately contentful states. "We have no reason to doubt," Fodor says, "that it is possible to have a scientific psychology that vindicates commonsense belief/desire explanation."

" Qualia " is an unfamiliar term for something that could not be more familiar to each of us: the ways things seem to us. As is so often the case with philosophical jargon, it is easier to give examples than to give a definition of the term. Look at a glass of milk at sunset; the way it looks to you--the particular, personal, subjective visual quality of the glass of milk is the quale of your visual experience at the moment. The way the milk tastes to you then is another, gustatory quale, and how it sounds to you as you swallow is an auditory quale; These various "properties of conscious experience" are prime examples of qualia. Nothing, it seems, could you know more intimately than your own qualia ; let the entire universe be some vast illusion, some mere figment of Descartes' evil demon, and yet what the figment is made of will be the qualia of your hallucinatory experiences. Descartes claimed to doubt everything that could be doubted, but he never doubted that his conscious experiences had qualia, the properties by which he knew or apprehended them.

The idea that a computer could be conscious--or equivalently, that human consciousness is the effect of some complex computation mechanically performed by our brains--strikes some scientists and philosophers as a beautiful idea. They find it initially surprising and unsettling, as all beautiful ideas are, but the inevitable culmination of the scientific advances that have gradually demystified and unified the material world. The ideologues of Artificial Intelligence (AI) have been its most articulate supporters. To others, this idea is deeply repellent: philistine, reductionistic (in some bad sense), as incredible as it is offensive. John Searle's attack on "strong AI" is the best known expression of this view, but others in the same camp, liking Searle's destination better than his route, would dearly love to see a principled, scientific argument showing that strong AI is impossible. Roger Penrose has set out to provide just such an argument.

What do these various heresies have in common? From Fodor's point of view, two things, obviously: (1) they are all wrong, wrong, wrong! and (2) they are endorsed by people who are otherwise quite decent company. That would be thread enough to tie Fodor's targets together if he were right, but as one who finds more than a morsel of truth in each of the derided doctrines, I must seek elsewhere for a uniting principle, and I think I have found it: they are all doctrines that make Fodor's Granny exclaim "Well I never!" and lurch alarmingly in her rocker. The cat is out of the bag. Jerry Fodor is a Granny's boy, a romantic conservative whose slogan might well be.

These are heady times for the sciences of the mind. The pace of discovery is quickening, thanks to the mountain of data provided by the new brain-imaging technologies, but thanks even more to the computer simulations that have expanded and disciplined our imaginations, dramatically enlarging the logical space of models that can be investigated. We can now seriously consider hypotheses that a few years ago were simply unframable--"inconceivable", a philosopher might have been tempted to say. These computer-expanded powers are being vigorously exploited by a new generation of theorists and experimentalists. In some quarters the first symptoms of gold rush fever have been detected.

In 1982, Feldman and Ballard published "Connectionist models and their properties" in Cognitive Science, helping to focus attention on a family of similarly inspired research strategies just then under way, by giving the family a name: "connectionism." Now, seven years later, the connectionist nation has swelled to include such subfamilies as "PDP" and "neural net models." Since the ideological foes of connectionism are keen to wipe it out in one fell swoop aimed at its "essence", it is worth noting the diversity of not only the models but also the aspirations of the modelers. There is no good reason to suppose that they all pledge allegiance to any one principle..

Are there really beliefs? Or are we learning (from neuroscience and psychology, presumably) that, strictly speaking, beliefs are figments of our imagination, items in a superceded ontology? Philosophers generally regard such ontological questions as admitting just two possible answers: either beliefs exist or they don't. There is no such state as quasi-existence; there are no stable doctrines of semi-realism. Beliefs must either be vindicated along with the viruses or banished along with the banshees. A bracing conviction prevails, then, to the effect that when it comes to beliefs (and other mental items) one must be either a realist or an eliminative materialist.