## Saturday, November 6, 2010

### Colors and time

I am inclined to think we are four-dimensional (or, more precisely, (n+1)-dimensional, where n is whatever number of dimensions space turns out to have) beings, but that we do not have temporal parts. So what do I say about apparently monadic properties that one can change in respect of, like being red? My preference is to say that these properties are, in fact, non-monadic. For instance, "I am beige" (or whatever color term correctly indicates the current typical shade of my skin) expresses the fact that I beigely occupy the present, where the present is a spacelike hypersurface.

Presentists can say, more simply, that "I am beige" expresses my being beige simpliciter. So it seems that on theoretical simplicity grounds, presentists win out. But I think this is mistaken. For whereas presentists need to posit two properties—a monadic being beige and a binary beigely occupying—eternalists of my sort need only posit a single binary property of beigely occupying. (Of course, the presentist could analyze her being beige in terms of beigely occupying the present, but then the presentist loses the advantages of the theory.)

Here is a reason why the presentist needs a binary beigely occupying. I am beige on my left half. (I am also beige on my right half, but nevermind that.) Given a relational beigely occupying, I can let L be the region of spacetime occupied by my present left half, and analyze "I am beige on my left half" as "I beigely occupy L." But this uses the relation of beige occupation.

I do not think this can be done with mere monadic beigeness. The best way I know of rendering "I am beige on my left half" in terms of monadic beigeness is something like "My left half is beige." But there is no such object as my left half. Cutting me in half is not cutting nature at its seams, and if there are such things as parts at all, they are obtained by cutting nature at its seams. But it's worse than that. Suppose there were such an object as my left half. It wouldn't be beige! For one of that object's surfaces—the one where the object meets my right half—would be mainly bloody red.

One might try to talk of the left half of my surface being beige. But a surface has two sides, which can have different colors, and so we would still need a non-monadic property: being beige on the outside/inside. Or at least a pair of monadic properties. But not just the plain monadic being white. Besides, I don't think we have surfaces. Those would be weird things in the case of beings whose material components are made up of particles or that have blurred wavefunctions.

So, the presentist also needs beige occupation in addition to beigeness. But isn't it simpler to just analyze the latter in terms of the former?

Mike Almeida said...

Interesting problem. The worry for your account is that being beige is not a relation. So we have relations running into intrinsic properties. I don't know how much pressure you feel to preserve the commonsense cuts between intrinsic properties and relations.

The presentist seems to have an alternative. Suppose he says that the matter occupying the region loosely called his left side is beige. He is not thereby committed to the thesis that there is an object there. He would be saying something like the matter that occupies the region of all the toilets in NY is beige. He does not have to say that there is an object there composed of all of the toilets.

Alexander R Pruss said...

So many seemingly intrinsic properties turn out not to be intrinsic that I am not worried about preserving the distinction.

So for the presentist alternative, that matter is not beige. Most of it is blood red. It is only beige along those surfaces that are also my surfaces.

Mike Almeida said...

So for the presentist alternative, that matter is not beige. Most of it is blood red. It is only beige along those surfaces that are also my surfaces.

We've got to be careful moving back and forth from ordinary talk and stricter talk. Ordinarily, we want to say that the matter is beige, despite the blood red portion. Just as ordinarily we want to say that a ball is red when it's surface is red, and most of it (beneath of the surface) is black. But to speak more strictly, let me dub Bob's visible surface matter on his left side BobL. The presentist can say strictly that BobL is beige.

Alexander R Pruss said...

How thick is BobL? If it's one-molecule thick, it's not beige, but transparent. If it's thick enough to be beige on one side, it might very well (for all we know) be red on the other side.

Mike Almeida said...

How thick is BobL?

Is htis a genuine problem, Alex. Let BobL be as thick as the depth of beige molecules. BobL will likely not have determinate borders, but that's I think not a big worry.

Alexander R Pruss said...

Yes, I think it is a genuine problem.

In order to use BobL to analyze the claim "My left half is beige", we need a specification of BobL. The suggestion seems to be: "My left half is beige" is true iff "The molecules at the surface of my left half, together with any additional layers of beige molecules there may be, are collectively beige."

But the analysis is implausible. First, colors can arise in a variety of ways. An object can beige without any beige molecules. For instance, it will be beige if it is made of a red, green and blue molecules of equal sizes mixed up in a 245:245:220 ratio. (Maybe you could say that it only looks beige, but isn't actually beige. But I don't think that can be sustained.) I could also be beige on my left half by having a thin cyan skin overlaid on a glowing red underlayer.

An object can also gain a color in other ways. If I take a flat piece of optical glass, and paint a layer of MgF2 of uniform 138nm thickness, the
glass will look purplish-blue, even though the glass itself is colorless and MgF2 is colorless. Or take the colors that are obtained by anodizing Titanium. These colors result by depositing an oxide layer of the right thickness.

Mike Almeida said...

The best way I know of rendering "I am beige on my left half" in terms of monadic beigeness is something like "My left half is beige."

This is your best way of rendering "I am beige on my left side", and it is subject to the very same objections you're advancing against my account. Pressing the issue "exactly what pieces of matter have to be beige in order for something to be beige" is a problem for any view about some bit of matter being beige (or any other color). If pressed, I would say (as we all ordinarily say) that the matter in spatial location L is beige iff. it appears so (under the standardly specified ideal conditions). That's not an ideal analysis, but no one else has an ideal analysis either. So S is beige on his left side iff. S appears to be beige on his left side. You'll object: but he's red on the inside. I'll respond: that's irrelevant ot the question of whether he is beige on the left side (as with the red ball that is black on ths inside).

Alexander R Pruss said...

I agree that my best monadic analysis also has the problem I am pointing out. What I am trying to argue is that we need a non-monadic analysis. Your suggestion "S appears to be beige on his left side" is non-monadic: it involves S and a location (the left side).