On Fri, Oct 16, 2015, at 03:44 PM, ... wrote:
> Hello Professor Pryor~
> 
> When the physicalist say that " nothing happens in or to a person's body
> except what conforms to physical and chemical laws; the physical world is
> causally closed", does he automatically support determinism?

Hi ..., it is *natural* to interpret the physicalist that way. I think
a *natural first reading* of the argument would understand the
physicalist to be saying, there are always physical causes that UNIQUELY
DETERMINE that the physical effect had to happen, so if there's also
some additional mental cause, then the effect is OVERDETERMINED. (Notice
the language: they say overDETERMINED.) Thus, if one thinks that
determinism is false, as perhaps our best current physics requires (it
is controversial whether physics requires this, but maybe it does), then
the physicalist's argument, read in this way, would have a false
premise. So the dualist could then say, "See, your argument has a false
premise. So I don't have to worry about it."

However, I think it is possible to read the physicalist's argument in a
subtler way where they aren't committing themselves to determinism, and
so the dualist can't get off the hook so easily if determinism turns out
to be false. That's how I was trying to present the physicalist's
argument in class. They might be saying, not that the earlier physical
causes UNIQUELY DETERMINE that the physical effect had to happen, but
rather that the physical causes are ENOUGH TO CAUSALLY EXPLAIN the
physical effect---or at least to explain all there is about it that's
explicable. Even if determinism is false, we should still think that the
past causally explains the future. It should at least tell us what the
probability was that the future would be some specific way, and we
should see patterns of results that in the long run tend to match these
probabilities. So maybe the physicalist can still push this argument
through without committing themselves to determinism. I admit though
that the argument is more straightforward when the physicalist assumes
determinism is true. Making the argument work without relying on the
assumption of determinism is harder.

I know these issues are complex, but I hope that helps clarify them a
bit.