The Cartesian Theatre

I recently read Daniel Dennett's Consciousness Explained. It's a great book, I highly recommend it. Here begins a short series of posts outlining the ideas in the book that I found most interesting.

Dennett is highly critical of the common-sense belief in a 'Cartesian theatre' - a place in the brain where "it all comes together" and consciousness occurs. Dennett argues that this outmoded view should be rejected alongside dualism, despite its intuitive pull.

Cartesian materialism is the view that there is a crucial finish line or boundary somewhere in the brain, marking a place where the order of arrival equals the order of "presentation" in experience because what happens there is what you are conscious of. [...] Many theorists would insist that they have explicitly rejected such an obviously bad idea. But [...] the persuasive imagery of the Cartesian Theatre keeps coming back to haunt us - laypeople and scientists alike - even after its ghostly dualism has been denounced and exorcized. [p.107, original emphasis.]

The immediate problem, as I understand it, is that such a 'special center' is neurologically implausible. Cognitive processing is spread throughout the brain, there is no specific region containing all and only the information we are consciously aware of.

This then gives rise to a logical problem, when we try to categorise events as either 'not yet observed' or 'already observed'. To quote Dennett again:

If the "point" of view of the observer must be smeared over a rather large volume in the observer's brain, the observer's own subjective sense of sequence and simultaneity must be determined by something other than "order of arrival," since order of arrival is incompletely defined until the relevant destination is specified. If A beats B to one finish line, but B beats A to another, which result fixes subjective sequence in consciousness?

Lastly, there is a philosophical problem, in that Cartesian materialism commits one to uphold the appearance/reality distinction even about the subjective. That is, it implies that there is a difference between that which really seems to be so, and that which merely seems to seem to be so. Dennett doubts there is any such distinction to be made, and I'm inclined to agree.

Dennett raises a parallel distinction between what he calls 'Orwellian' and 'Stalinesque' revisions. Suppose I remember seeing something that wasn't really there. Cartesian materialism implies that there are two ways this could happen: the false information could either be inserted before my conscious experience (so a Stalinesque show trial is performed in my 'theatre'), or else after it, manipulating my memories in an Orwellian rewriting of history. In the one case you accurately remember a hallucination; in the other, you have false memories about your "real" experience.

This strikes us as a genuine distinction - and so it is, on the 'macro' time scales that we are used to. But once we zoom in to the micro level of neurological events, we find the subject's point of view becomes "spatially and temporally smeared". So we are wrong, Dennett argues, to assume we can uphold this distinction 'all the way in' (as the Cartesian materialist must). On these smaller scales, the distinction no longer appears meaningful:

[W]e can suppose, both theorists have exactly the same theory of what happens in your brain; they agree about just where and when in the brain the mistaken content enters the causal pathways; they just disagree about whether that location is to be deemed pre-experiential or post-experiential. [...] [T]hey even agree about how it ought to "feel" to subjects: Subjects should be unable to tell the difference between misbegotten experiences and immediately misremembered experiences. [p.125, original emphasis.]

So, Dennett concludes, the difference between Orwellian and Stalinesque theories is merely verbal, a matter of arbitrary semantics. "This is a difference that makes no difference." It harks back to that bizarre category of the 'objectively subjective'. But, as Dennett notes, "Putative facts about consciousness that swim out of reach of both 'outside' and 'inside' observers are strange facts indeed." (p. 133)

Next up, I will discuss Dennett's proposed alternative to Cartesian materialism: the Multiple Drafts model.