Thursday, December 19, 2013

A simple consequence argument

Say that p and q are nomically equivalent provided that the laws of nature entail that p holds if and only if q does.


  1. If q is not up to you, and p is nomically equivalent to q, then p is not up to you.

Suppose determinism. Let L be the laws. Let t0 be 1000 years ago. Let p be a proposition reporting something you do. Let q be the disjunction of all the nomically possible states of the universe at t0 that evolve under L in such a way as to make p true. Then, plausibly:

  1. p and q are nomically equivalent.
For given the deterministic laws, if p is true, then a thousand years ago the universe must have been such as to have to evolve to make p true.[note 1] And conversely, the laws entail that if it was such, then p is true.

Finally, observe that events a thousand years ago aren't up to you:

  1. q is not up to you.

We conclude that p is not up to you. So no actions are up to you if determinism holds.


Mr. Green said...

Just for fun, I'm going to challenge (3): supposing (physical) determinism and free will are both true, God can make the universe consistent via some sort of pre-established harmony, i.e. His fine-tuning of the universe is based on the free actions He foresees me (and everyone else) doing. Thus events a thousand years ago are due to me (and everyone else, but I'm happy to share the credit!).

Sam said...

I guess that depends on what you mean by "up to you." It seems to me that given any deterministic causal chain, every link in the chain affects what happens later. If determinism is true, and if I am a link in the deterministic causal chain, then I have everything to do with what happens in the future.