Tuesday, April 06, 2010

Supervenience, selfhood, and physicalism

The supervenience principle (a central principle of minimal materialism) says there is no difference between possible worlds without a physical difference. But it seems to me that the world could be physically identical to this one, but the person in it who is the psychological center of it, the "me", as it were, could be living in the White House instead of in Glendale, Arizona. Or indeed, I could have lived 1000 years ago and be dead by now. There is a contingent truth that I am Victor Reppert and not some other person. For every person there seems to be a contingent fact that they happen to be in that inner world and not some other inner world. And if that is the case, then it looks to be as if there are truths about the world that are not explained by the set of physical truths.

This does seem explicable if what is at the base of reality is more like a mind than anything else. But if what is at the base of reality is more like a rock than anything else, how do these contingent facts emerge? It looks logically impossible to me.


Anonymous said...

One problem I have with these sorts of principles is that it ignores how much dispute there is over what comprises the physical. What it means to be "like a rock" has changed quite a lot in ultimate senses since quantum mechanics came on the scene. I can picture someone agreeing that what you speak of is possible, but still insisting that the difference you speak of is a physical difference - because "physical" is now so wide-open as a term.

Victor Reppert said...

Well, there are certain things that have to be excluded from the basic level of the "physical" if "physical" is going to mean much of anything. If you get too liberal about what counts as physical, then I am going to ask why you can't baptize the metaphysics of traditional Christianity into physicalism. I have argued that intentionality, normativity, subjectivity, and purpose have to be keep off the ground floor of reality if reality is to be physicalistic in any meaningful sense.

I mean, you need some sort of explanation as to why God, (otherwise known as the Theon), can't be brought into physicalistic explanations. I take it you want to exclude the Theon on principle, not by fiat.

Anonymous said...

Actually, I'm agreeing with you across the board (that certain things have to be excluded from "physical" to mean anything, and that what you outline are traditionally among the things that have always been so excluded, etc.)

I'm only adding that I think, for many, "physicalism" really has lost quite a lot of meaning. Go right to the SEP entry on physicalism, and right at 11.3 you'll see an example of what I mean. Not the problem mentioned, but the response to it.

Victor Reppert said...

That's why you've got to hold physicalists' feet to the fire and make them give you an account of what they believe that really does exclude something. If you look at the way I develop the AFR, especially in the Blackwell Companion to Natural Theology, and also in the shorter essay in Contenting with Christianity's Critics, you will find that I start with a basic definition of a naturalistic view.

Otherwise, you get people "solving" problems for naturalism by saying "the brain this, the brain that," as if using the magic word "brain" guarantees that everything is naturalistically hunky-dory.

Anonymous said...

I'm not a naturalist/physicalist/materialist by *any* stretch of the imagination but isn't the following principle that "...there is no difference between possible worlds without a physical difference..." a *strong* construal of supervenience?

Couldn't a physicalist just hold to a *weak* supervenience principle?