Thursday, January 10, 2013

An argument that consciousness is reducible

Suppose that over the next hour, you are consciously and constantly perceptually aware of a red wall, while I am consciously aware of nothing red—I am in a room where everything is blue—except that for exactly one nanosecond, half way through the hour, I have induced in me your intrinsic mental state, followed by a restoration of my previous state. Thus, if I was consciosu of something red during that nanosecond, I don't remember it afterwards.

But was I ever conscious of something red? I doubt it. A mental state that short just "doesn't register". Plausibly, given how humans are constituted, there just is no such thing as a pain that's only a nanosecond long, and there is no such thing as a consciousness of red that's only a nanosecond long.

But this yields the following argument, where we stipulate that a state is "near-instantaneous" provided that it has a temporal dimension of at most a nanosecond:

  1. All our intrinsic states are reducible to our near-instantaneous intrinsic states. (Premise)
  2. Humans have no near-instantaneous intrinsic state of being conscious of red. (Premise, justified by the thought-experiment)
  3. Being conscious of red is an intrinsic state of us. (Premise)
  4. So, a human's being conscious of red is reducible to near-instantaneous states that are not themselves consciousnesses of red.
But what goes for consciousness of red goes for all conscious states. So all conscious states are reducible to near-instantaneous states. But, plausibly, we have no near-instantaneous conscious states. So all conscious states are reducible to states that are not conscious states.

If this argument is right, then qualia are reducible. It does not, however, follow that they are reducible to physical states. It could, instead, be the case that conscious states are reducible to fundamental mental states that are not conscious states. The hard problem of mind is the problem of intentionality, perhaps, not the problem of consciousness (a sentiment I think I have heard from more than one person).

But all that said, I am not sure of premise (1) in the argument above. And I am not completely sure that the thought experiment succeeds. Maybe one can say that one is near-instantaneously aware of red but one forgets it right away. I don't know.


Mr. Green said...

I'm also not sure of (1). In the science lab, we can observe physical reducibility, but it's not clear to me that we can apply that to consciousness without begging the question; that said, it doesn't seem implausible to me. But I'm even less sure of (2). Our bodies cannot register near-instantaneous states, but all that means is that our apparatus has limited precision. If I could get an instantaneous experience into my mind (e.g. by God's zapping it there, or maybe via a resurrected body), then why shouldn't I be conscious of it?

William said...

The neuron's action potential is an all-or-nothing response, where each nanosecond-at-a-time change causing a tendency to depolarization does nothing until enough such miniscule changes add up to then cause a sudden all-or-nothing depolarizing response, which is then prolonged over a long period.

By analogy, a nanosecond change would do nothing unless it was somehow enough to tip consciousness toward a new state, in which case that feeling would then last much longer than a nanosecond.

It's kind of a genuine (not just a verbal) sorites.

Alexander R Pruss said...

"in which case that feeling would then last much longer than a nanosecond"

Not if the previous state were miraculously restored (or just restored via an astronomically unlikely quantum transition).

William said...

"Not if the previous state were miraculously restored"

True, i was assuming we had just a single intervention event and that consciousness went on from there. I do think there is a limitation to how fast we can think of something: the literature on subliminal stimuli imply that a flicker lasting for less than a millisecond is not even perceived unconsciously. The distinctions would then be between no change, subliminal unconscious change, and conscious change, depending I suppose on the durations allowed.

The reduction still is more one of discrete boundary transitions and not gradual buildup of a conscious state. This might fit an emergence schema, possibly due to some underlying structure that needs to reach threshold.

Nathan Coppedge said...

Clearly to me there is the linear causality problem. While we may feel we need to argue inductively or a posteriori to get a rational chain of events, these events can easily occur without our arguing as such. This speaks of an irreducible 'thisness', haecceity, or being-there-ness which may be associative and correspondent. For example, I cite a problem that correspondence is one of the most irreducible things. It can be reduced, but the product is a disaster. In real life our brains need a lot of correspondence to find basic coherence. While coherence and correspondence may increase (perhaps infinitely?) the basic functions of each are not present at every level. Thus when you speak of nanoseconds of red, I don't find this conducive to nanoseconds of the absence of red. A corollary for this is that the red 'does' have a real effect, however small. For example, at some point, whether it is 12 nanoseconds or 12 million nanoseconds, there will be a conscious impression of the color red. But this is not to say that there is no unconscious impression, which is to say still less that the nanosecond of red had no effect at all. Instead, we simply have to admit that a nanosecond of red is a very small effect of the color red.

Perhaps where you were confused was that, much as loading a (perhaps infinite?) screen, if there is an entire field of red, then this field is more likely to register than a single point of red in the same time frame. I think the answer to this is that, due to some aspects of physical law, it is simply impossible to register an entire field of red in a nanosecond. Instead, it registers as a diffuse field, with some red occurring in one nanosecond and some in the next. If this were not the case, the field would be infinitesimal.

Another argument is that there is a difference between the photons which register in our eyes, and the light of imagination which registers as a mental impression. I would say, that similar to a theory introduced in the book Moral Machines, at a certain point the brain (or computer, following a similar theory) accepts or rejects the entire pattern of information. But there are multiple points before, when the information can be accepted or rejected before it makes an impression. And there is an intermediate point when the impression can be accepted without being an 'official' impression. Yet at every meaningful stage, there are correspondences, which means that there is no case in which the field of red simply 'materializes' as its own singular condition; in every stage, there is a mental effect of some kind, even if many of these stages do not 'trigger' or 'implement' the visual field of red. It helps to consider that vision is used as a mental tool which works inwards-to-outwards (top down) rather than outwards-to-inwards (bottom up). Even if there is some recursion, the locus of changing the visual effect is mental rather than environmental. I think that resolves some of your conundrum.