Tuesday, May 25, 2010

multiple-drafts theory of consciousness

From Key Terms in Philosophy of Mind (Continuum, 2010):
multiple-drafts theory of consciousness, due to Daniel DENNETT, a theory of CONSCIOUSNESS consistent with PHYSICALISM wherein a conscious state (see CONSCIOUSNESS, STATE) is spread out in both space and time in the brain across multiple instances of what Dennett calls “content fixations” (see MENTAL REPRESENTATION), each of which—the “multiple drafts”—compete for domination in the cognitive system or what Dennett calls “fame in the brain.” Crucial to Dennett’s account of consciousness is a denial of the existence of what he calls “the Cartesian theater”—a single place in the brain where at some specific time which is the onset of consciousness, “it all comes together.” The Cartesian theater is where the various previously unconscious brain events march onto the stage of consciousness before the audience of a HOMUNCULUS who watches the passing show. Dennett regards such a positing of a homunculus as nonexplanatory: How is the homunculus conscious of the show in the Cartesian theater?

Many of the considerations that Dennett provides in support of the multiple-drafts theory hinge on features concerning the application of the CONTENT/VEHICLE DISTINCTION to conscious representations of time. Such representations may themselves (the vehicles) occur at times other than the times that they are representations of (the contents). The importance of the content/vehicle distinction for time representation can be drawn out in contemplation of an
argument Dennett gives concerning the illusory motion and illusory color- change in an effect known as the color-phi phenomenon. In the color-phi phenomenon, the subject is presented with a brief flash of a green circle, followed by a brief flash of a red circle. The two flashes occur in slightly different locations. Subjects report the appearance of motion: a green circle, that moves and becomes red at the point roughly between where the green circle was flashed and where the red circle was flashed. Especially interesting is that subjects report that the green circle turns red before arriving at the spot where the red circle is flashed. The subjects cannot have known ahead of time that a red circle was going to flash, so how is it that they are able to have a conscious experience of something turning to red prior to the red circle’s
flashing? One candidate explanation is that the subject unconsciously perceives the red circle’s flash and the subject’s brain uses that INFORMATION to generate an illusory conscious experience of a green circle changing to red. Another candidate explanation is that the subject consciously perceived only the nonmoving green and red circle flashes and has a false memory of there having been a moving and color-shifting circle. Dennett argues that there is absolutely no basis for preferring one of these candidate explanations over the other. According to Dennett, there is no fact of the matter about consciousness aside from how things seem to the subject (see APPEARANCE), and how things seem to the subject is determined by the BELIEF that is arrived at via the process, smeared out in space and time in the brain, of competitions for fame in the brain via multiple content fixations. Some of Dennett’s critics have accused his argument here of relying on an untenable VERIFICATIONISM.