Monday, December 14, 2015

Thinking big numbers

If physicalism is true, then the nature of human beings is probably essentially tied to the nature of our brains, which in turn is essentially tied to the laws of nature. So a human being couldn't have a radically transformed brain. But there are limits on the information storage of our brains. This makes plausible the first premise of the following valid argument:

  1. If physicalism is true, there are only finitely many integers that it is metaphysically possible for humans to think about (without externalist crutches).
  2. It is metaphysically possible for humans to think about any integer (without externalist crutches).
  3. So, physicalism is not true.
Of course, the controversial premise is (2), and I wouldn't worry too much about the argument if I were a physicalist. But, still, there is some plausibility to (2), so the argument has some little force.


entirelyuseless said...

I think there is a problem with this whole chain of thought. If physicalism is true, then the identity of a human individual is probably like the identity of a chair or some other physical object. In other words, it is a question of physical and psychological continuity. In this case, you could have a radically transformed brain as long as you managed to remember having the non-radically transformed brain, and you would still keep your numerical identity. If this is right, the argument fails by assuming a kind of human nature and identity which is not the kind posited by physicalism.

Alexander R Pruss said...

But there is nothing in the argument about numerical identity. It is a claim about humans.

Richard Davis said...

Alex, would you take physicalism to be compatible with a human thinking any integer, no matter how large, but in cases of sufficiently large ones, only after ceasing to be human?

I suppose I'mean asking, is physicalism compatible with the combined claims:

For every human x, there is some integer n such that necessarily, when x is human, x does not think n.
Nevertheless, x is human at time t, and for every integer n, possibly x thinks n sometime after t.

The key is that perhaps x possibly ceases to be human.

Richard Davis said...
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