Synchronization and the unity of consciousness

The problem of the unity of consciousness for materialists is what makes activity in different areas of the physical mind come together into a single phenomenally unified state rather than multiple disconnected phenomenal states. If my auditory center active in the perception of a middle C and my visual center is active in the perception of red, what makes it be the case that there is a single entity that both hears a middle C and sees red?

We can imagine a solution to this problem in a computer. Let’s say that one part of the computer has and representation of red in one part (of the right sort for consciousness) and a representation of middle C in another part. We could unify the two by means of a periodic synchronizing clock signal sent to all the parts of the computer. And we could then say that what it is for the computer to perceive red and middle C at the same time is for an electrical signal originating in the same tick of the clock to reach a part that is representing red (in the way needed for consciousness) and to reach a part that is representing middle C.

On this view, there is no separate consciousness of red (say), because the conscious state is constituted not just by the representation of red (say) in the computer’s “visual system”, but by everything that is reached by the signals emanating from the clock tick. And that includes the representation of middle C in the “auditory system”.

The unification of consciousness, then, would be the product of the synchronization system, which of course could be more complex than just a clock signal.

This line of thought shows that in principle the problem of the unity of consciousness is soluble for materialists if the problem of consciousness is (which I doubt). This will, of course, only be a Pyrrhic victory if it turns out that no similar pervasive synchronization system is found in the brain. The neuroscience literature talks of synchronization in the brain. Whether that synchronization is sufficient for solving the unity problem may be an empirical question.

The above line of thought also strongly suggests that if materialism is true, then our internal phenomenal timeline is not the same as objective physical time, but rather is constructed out of the synchronization processes. It need not be the case for this that the representation of red and the representation of middle C happen at the same physical time. A part further from the clock will receive the synchronizing signal later than a part closer to the clock, and so the synchronization process may make two events that are not simultaneous in physical time be simultaneous in computer time. I suspect that a similar divide between mental time and physical time is true even if dualism is (as I think) true, but for other reasons.

Relativity, brains and the unity of consciousness

I was grading undergraduate metaphysics papers last night and came across a very interesting observation in a really smart student’s paper on Special Relativity and time (I have the student’s permission to share the observation): different parts of the brain have different reference frames, and so must experience time slightly differently.

Of course, the deviation in reference frames is very, very small. It comes from such facts as that

• the lower parts of the brain are closer to a massive object—the earth—which causes a slight amount of time dilation, and

• we are constantly wobbling our heads in a way that makes different parts of the brain move at different speeds relative to the earth.

Does such a small difference matter? As I understand their argument, my student thought it would make the A-theory less plausible. For it makes it questionable whether we can say that we really perceive the true objective now in the way that A-theorists would want to say we do. That’s an interesting thought.

I also think the line of thought might create a problem for someone who thinks that mental states supervene on physical states. For consider the unity of consciousness whereby we are aware of multiple things at once. If the consciousness of these different things is partly constituted by different chunks of the brain, then it seems that what precise stream of consciousness we have will depend on what reference frame we choose. For instance, I might hear a sound and feel a pinch at exactly the same moment in one reference frame, but in another reference frame the sound comes before the feeling, and in other the feeling comes before the sound. But that seems wrong: the precise stream of consciousness should not depend on the reference frame.

This shows that if the order of succession within the stream of consciousness does not depend on the reference frame (and it is plausible that it does not), then the precise stream of conciousness cannot supervene on physical states. This is clear if there is no privileged reference frame in the physical world. But even if there is a metaphysically privileged reference frame as A-theorists have to say, it seems reasonable to say that this frame is “metaphysical” rather than “physical”, and hence a dependence of consciousness on this frame is not a case of supervenience of mind on the physical.

Here is what I think we should say: If the A-theory is true, then the mind somehow catches on to the absolute now. If the B-theory is true, then the mind has its own subjective timeline, which is not the timeline of the brain or any part of it.

I think a really careful materialist might be able to affirm the latter option, by analogy to how in a modern digital computer, even though at the electronic hardware level there is analog time (perhaps itself an approximation to some frothy weird quantum time), synchronization of computation to clock ticks results in the possibility of abstracting a precisely defined discrete time that “pretends” that all combinatorial logic happens instantaneously. Roughly speaking, the assembly language programmer works with respect to the discrete time, while the FPGA programmer works primarily with respect to the discrete time but has to constantly bear in mind the constraints that come from the underlying analog time. However, the correspondence between the two levels of time is only vague. Similarly, I think that it is likely that the connection between the mind’s timeline and the physical timelines is going to suffer from vagueness (though perhaps only epistemic). How philosophically happy a materialist would be with such a view is unclear, and there is a serious empirical assumption here for the materialist, namely that the brain has a global synchronizing process similar to a microprocessor’s or FPGA’s synchronizing clock. I doubt that there is, but I know very little of neuroscience.