Free will

Let us now see what can be done about defining free will.
I use the term 'free will' out of respect for tradition.

When I say of a man that he "has free will" I mean that very often, if not always, when he has to choose between two or more mutually incompatible courses of action — such that he can, or is able to, or has it within his power to carry out.

It is in these senses that I shall understand 'free will' and 'determinism'. I shall argue that free will is incompatible with determinism. It will be convenient to call this thesis incompatibilism and to call the thesis that free will and determinism are compatible compatibilism.

I have no use for the terms 'soft determinism', 'hard determinism; and 'libertarianism'. I do not object to these terms on the ground that they are vague or ill-defined. They can be easily defined by means of the terms we shall use and are thus no worse in that respect than our terms.
van Inwagen does not seem to mind that "incompatibilism" lumps together opposite schools – hard determinists and libertarians.

Soft determinism is the conjunction of determinism and compatibilism; hard determinism is the conjunction of determinism and incompatibilism; libertarianism is the conjunction of incompatibilism and the thesis that we have free will.

I object to these terms because they lump together theses that should be discussed and analysed separately. They are therefore worse than useless and ought to be dropped from the working vocabulary of philosophers.

'Contra-causal freedom' might mean the sort of freedom, if freedom it would be, that someone would enjoy if his acts were uncaused. But that someone's acts are undetermined does not entail that they are uncaused.

Incompatibilism can hardly be said to be a popular thesis among present-day philosophers (the "analytic" ones, at any rate). Yet it has its adherents and has had more of them in the past. It is, however, surprisingly hard to find any arguments for it. That many philosophers have believed something controversial without giving any arguments for it is perhaps not surprising; what is surprising is that no arguments have been given when arguments are so easy to give.
Perhaps the explanation is simply that the arguments are so obvious that no one has thought them worth stating. If that is so, let us not be afraid of being obvious. Here is an argument that I think is obvious (I don't mean it's obviously right; I mean it's one that should occur pretty quickly to any philosopher who asked himself what arguments could be found to support incompatibilism): we call this the Determinism Objection.

If determinism is true, then our acts are the consequences of the laws of nature and events in the remote past. But it is not up to us what went on before we were born, and neither is it up to us what the laws of nature are. Therefore, the consequences of these things (including our present acts) are not up to us.

I shall call this argument the Consequence Argument.