This Wednesday David Rosenthal will be giving  a talk at the Graduate Center entitled ‘The Poverty of Consciousness’. If you happen to be in the New York Area and you have a hankering for some hot and heavy philosophy of consciousness, come on down! (see the Cog Blog for some details).

I have been thinking about this issue and in light of my last post on priming and change blindness where I voiced my suspicion that the results posed a problem for Rosenthal’s claim about the function of consciousness. This lead to soem emailing between David and I and so I figured I would take some time to sort this stuff out.

Rosenthal’s main contention is that there is no evolutionary (read: reproductive)advantage to an organism’s having consious mental states. This is to be distinguished from the claim that there is no evolutionary advantage to the animal being conscious (creature consciousness), which quite obviously gives the creature a huge evolutionary advantage (e.g. being awake often helps one get away from predators…that is unless one has taken ambien!!!). The primary reason that he thinks this is because he endorses the higher-order theory of consciousness which claims that a mental state is conscious when I am conscious of myself as being in that state (and of course there is some experimental results which support the claim 🙂 ). This view commits one to the claim that any mental state can in principle occur unconsciously and this seems to suggest that most of a states causal powers will be had by the state whether it is conscious or not. If so then what purpose could (state) consciousness add?

When people hear this they usually think that it means that consciousness is completely epiphenomenal (has no causal efficacy). But this isn’t right, as I discussed in this post on Uriah Kriegal’s version of this argument. As Rosenthal says, 

Lack of function does not imply that the consciousness of these states has no causal impact on other psychological processes, but that causal impact is too small, varied, or neutral in respect of benefit to the organism to sustain any significant function. So my conclusion about function for does not imply epiphenomenalism.

His claim is that whatever causal powers a state’s being conscious endows it with they are too ‘small, varied, or neutral with respect to benefit’ to count as serving any function. O.K., so if this is your view then you have your work cut ouot for you because you have to A.) examine and refute all of the proposed functions for consciousness out there (from ‘deliberate control of action and rational inference’ to ‘enhances creativity’) and B.) provide an alternate explanation for how in the world conscious mental states ever cam about in the first place (tune in on Wed. to hear Rosenthal’s answers to these questions, though I gather that he will mostly be talking about intentional states and not qualitative states).

O.K., so now enter the priming results that I talked about previously (and which Rosenthal is aware of and has read and cites in his forthcoming papers/book on this subject). What that paper showed is that when one is presented with two pictures. A and B, which have some difference between them (like an extra tree or something), D, then when one is presented with A and B and one is not conscious of the difference then both A and B show priming effects (i.e. one will complete a degraded picture with what one unconsciously saw in A and B) but when one consciously notices that there is a difference between A and B then only B (i.e. not A) shows priming effects.

Now, if this is evidence for anything it will be evidence for there being a function for preceptual states (qualitative states). It would still be an open question, what, if any, function intentional states have (unless of course one, like me, thinks that intentional states are qualitative states). But is it evidence for a function of conscious states?

I suggested that it is evidence that a state’s being conscious inhibits previous ‘outdated’ representations and so serves to guide certain representations (i.e. the conscious ones) to greater causally efficacy and so to greater effect on behavior. If this were true, it seems to me that that would definitely give some evolutionary advatage to having conscious states. Suppose, for instance, that a bear is charging at you and that there is a spear that is just out of reach. The bear is running straight at you and you are casting frantically about for something to defend yourself with. As you look around, wildly, you first see the spear out of reach, and then in another pass you see the spear within reach (say it was knowcked towards you in the chaos of the bear stampeding towards you). Now let us assume that in one case you do not consciously see this difference and in the other case you do. In both cases you will have representations of the scene with the spear out of reach and with the spear within reach. But only in the case that yo consciously see the change (that is, consciously see that the spear is not in reach). The previous representation is now inhibited and the representation of the spear is now moral causally active and liable to cause you to reach for the spear and (maybe!) stave of the bear. This doesn’t seem like some minor or neutral thing. This sounds like an important function for perceptual consciousness!

During our email discussion he reffered me to the following paper,

Fernandez-Duque, Diego, and Ian M. Thornton, “Change Detection without Awareness: Do Explicit Reports Underestimate the Representation of Change in the Visual System?“, Visual Cognition 7, 1-3 (January-March 2000): 324-344.

His argument seems to be that, while I am right that these results do suggest some ‘utility’ for conscious perceptual states, it is not as useful as change detection, and that can happen unconsciously! I am still thinking about that, and will come back to it…but right now I have to go and move my car for street cleaning!!!!