I'm reading Richard Taylor's "Freedom and Determinism" to prepare to grade some tests for two sections of Philosophy 201. Taylor makes the interesting observation that causal necessity is not the same thing as logical necessity. Causal necessity seems to imply something's being impossible given some set of natural laws and antecedent conditions. For example, "It is impossible for a person to live after having been decapitated," really means, "Given the realities of human physiology, a person's decapitation cannot fail to bring about that person's death." So the word "impossible" applies only to the actual world and its laws and conditions.
It is quite another thing to claim that it is logically impossible for a person to survive decapitation. That is because the word "impossible" in this sentence applies not only to this, the actual world, but to all possible worlds as well. That being the case, the proposition, "it is logically impossible for a person to survive decapitation," is patently false. It seems that there must be at least some possible world in which a person could survive decapitation. How about the possible world in which a person's brain is in their chest, and the head merely contains sensory organs? Decapitation in that world (given adequate medical attention, of course!) means the loss of 4 out 5 senses, but not death.
This suggests to me a conclusion that seems obvious, but has some startling implications: there is at least one possible world in which determinism does not obtain. That is, there is at least one possible world in which it is not the case that given any phenomena, that phenomena is the result of the operation of the laws of nature on antecedent conditions. That this is so seems plain: I can see no reason to suppose that determinism obtains in all possible worlds. What of the possible world in which some higher power controls every phenomena down to the smallest detail? Is it not the case that in this world phenomena are caused by that power and not by the laws of nature operating on antecedent conditions? What of the world without natural laws, where things operate together in completely random ways? I do not dispute that is difficult to imagine what such a world would be like, but I can see no reason to suppose that it is impossible that there is such a world.
Now, if it is the case that determinism is not logically necessary, and if that entails that there is at least one possible world in which determinism does not obtain, then we can legitimately ask the question, "How do we know that this, the actual world, is not such a world?" Admittedly, this question must seem nearly nonsensical given the commitment to determinism which seems so prevalent among philosophers. But unless determinism is logically necessary--and it is not--then it is a legitimate question to ask. And it is at this point that things become very interesting to me.
I can see no way, at the moment, to prove, beyond the shadow of a doubt, that this world is a world such that given any phenomena, that phenomena is a product solely of natural laws operating on antecedent conditions. There are certain presuppositions that I might hold that would dispose me to this sort of belief, of course. If I am a strict materialist, for instance (meaning that I believe that only physical things exist), then I am disposed to accept the determinist account. If I firmly believe that the empirical method is the only way to know anything, then perhaps I might be more inclined to accept the determinist position. But the take away here is that it is not at all certain that this is one of the possible worlds in which strict determinism obtains. Furthermore, it appears to me that any attempt to prove this would beg the question (certainly the scientific empiricist's reply seems that it would).
What I am left with, then, are two interlocking conclusions: given that there is some possible world in which determinism does not obtain, it remains an open question whether this, the actual world, is such a world. And if it is an open question whether determinism obtains, it will not do to simply assume that it is; an argument need be put forth. But, in at least my preliminary thinking on the matter, I can see no argument for determinism that is not hopelessly dependent on some other presupposition to provide the heavy lifting in the argument (e.g. materialism).
The trouble, though, is that the presupposition of materialism is just that: a presupposition. Attempts to prove this doctrine will founder on the shoals of question-begging: asserting that one has found no scientific evidence for non-material entities appears to me to be the height of question-begging. Similarly, attempting to prove that empirical observation is the only way to know anything seems doomed to fail, since if one believes that empirical observation is the only way to know anything, one will go about proving this assertion via empirical observation, which assumes the validity of the very thing in question.
The upshot of all this is that determinism seems to be a thesis that works for so many in virtue of the fact that it coheres with what they already believe, and not because it is the best thesis to explain the data at hand. Indeed, the very fact that I believe that I have a choice as to whether to continue writing this post or to get up and do something else shows at the very least that I have an intuition that runs contrary to the determinist thesis. Why, then, is it asserted as dogma by all but a very few within the philosophical community? I suggest that this is because determinism is the account of the world that best coheres with what they prefer to believe, and not because determinism is the account that best describes the world as it is.
