1.) if determinism is true, no one believes anything because they have a good reason for believing it.
I find this premise to be quite junky. What is “good reason” supposed to mean here?
But I can invalidate this premise even without a clarification of that term. For it may be fated that people think what they think, but that does not mean that, in every case, they think something to be true without justification.
Suppose we grant that our universe is deterministic. Do the people performing mathematical proofs now appear to be arriving at their conclusions without “good reasons”? The notion is absurd.
The invalidation of this premise alone is enough to explode the argument, but let’s take a look at the rest.
2.) if no one believes anything because they have a good reason for believing it, no beliefs are rational.
This premise seems true, since having some sort of “good reason” (i.e., justification) is a necessary condition of rationality.
3.)therefore, if determinism is true, no beliefs are rational, including the belief that determinism is true.
It’s a pretty simple syllogism and appears to be a validating argument. But the ambiguous first premise sinks it.
I argued in a recent thread that both “determinism” and “free will” are void concepts. I offer this thought experiment:
Universe A is deterministic. Universe B is not. What is the difference between the life of a person living in Universe A and Universe B?
The answer is that we can think of no possible difference, as the concept of “determinism” is not developed enough for us to imagine one. On the other hand, if we agree that probabilistic quantum phenomena are sufficient reason to deny that the universe is deterministic (by virtue of the definition of the term “deterministic,” whether or not the implications of this definition have actualy been imagined), then the whole question is moot anyway.