In Mind Time, Benjamin Libet develops the "Conscious Mental Field" (CMF) hypothesis to account for the metaphysical nature of the mind. CMF postulates that the mind is a distinct fundamental feature, or "quintessence," of the world, and has a distinctive role to play in organizing other phenomena, including neuronal activities.
The motivation for proposing the CMF hypothesis comes from Libet's hypothesis concerning free will: "free will does not initiate a volitional process; but it can control the outcome by actively vetoing the volitional process and aborting the act itself, or allowing (or triggering) the act to occur" (p.143). The first part of this hypothesis is supported by an experimental result in which the "readiness potential," i.e. the electrical charge which precedes an act, is temporally prior to conscious volition. In other words, the order of the sequence is: (1) electrical charge for an act; (2) conscious sense of "I will do this"; (3) actual act. Therefore, the will cannot initiate an act. On the other hand, the actual performance of the act comes after volition. Therefore, it is plausible to think that volition has some influence on how the readiness potential is translated into physical action. Moreover, according to Libet, the volitional charge itself may be "uncaused" in the sense that no necessary neuronal correlate has so far been found to precede that sense. What, then, is volition? This leads to Libet's hypothesis that volition might be part of a "conscious mental field" (CMF), a quintessential feature of the world which cannot be explained by another ground.
Libet suggests an experiment which may confirm the CMF hypothesis. Such an experiment would first isolate a part of the brain which is thought to be correlated to the functions of the CMF. These functions include the act of unifying various sensations into one continuous experience. (Readers of Kant can easily see that the functions of the CMF can almost completely correspond to the functions of judgement in the Critique of Pure Reason.) Next, the subject will report on the experience that he or she is having - for example, a new visual sensation might be introduced, and the subject might be asked to report whether that sensation is successively integrated into his or her awareness. If yes, next the experimenter observes the parts of the brain outside the isolated "CMF cortex" and see if there is any distinctive feedback. If yes, then this would strongly support the CMF hypothesis, since here we see one part of the brain influencing another without any direct physical connectivity available.
Libet does realize that there are many technical challenges to be surmounted before such an experiment might successfully be performed. (I wonder whether such an experiment already has been performed - Libet's book was published in 2002, so it is quite possible.) In any case, what I want to focus on is the applicability of this line of thought to artificial intelligence.
In artificial intelligence, one central philosophical question is whether computers can have consciousness. If we define consciousness as Libet's CMF (which is another name for Kant's "transcendental unity of apperception") then it becomes possible to design a test for determining whether computers are conscious or not.
If computers are conscious, then in this context this means that computers have a CMF. This in turn means that one part of a computer is able to influence another part of the computer without any direct physical connectivity between the two parts. Therefore, if it is possible to design a computer which performs such a feat, then this would strongly suggest that that computer is in possession of a CMF, and thus of consciousness. Libet does not explore this possibility in Mind Time, but I think that it is a very fruitful way of thinking about the question of whether computers can have consciousness
