Chisholm v. Classical Compatibilism: Part III

Sadly, the classical compatibilist derivation of PAPC from PAP will not apply in any straightforward way to the claim that you couldn't have decided to do anything other than what you did decide to do.

Here's a straightforward derivation:

You have the ability to decide otherwise.

Therefore, had you decided to decide otherwise you would have decided otherwise.

The problem is that it is not at all clear that the classical compatibilist's counterfactual analysis of ability (and hence practical modality) makes much sense here. If having the ability to decide otherwise requires that (in nearby metaphysically possible worlds) I decide to decide otherwise and so decide otherwise, I am doubtful I have this ability.

Chisholm v. Classical Compatibilism: Part II

As part of his argument that PAP is not equivalent to PAPC, Chisholm makes the following inference:

(1) You couldn't have decided to do anything other than what you did decide to do.

(2) Therefore, you could not have done anything other than what you did do.

This seems correct, but I've been wondering what one might do to resist Chisholm's inference.

What if "could" means different things in each line? The word "could" is a shifty beast and it can be hard to police. For example, if the first line asserts that it was morally impossible (i.e. forbidden) to decide otherwise, but the second line asserts that it was logically impossible to do otherwise, then the inference would equivocate in a way that would defeat the transfer of warrant from line 1 to line 2.

The classical compatibilist's view that we ought to understand PAP as PAPC rests on the thought that "could" here is a practical modality. I can do something if and only if I have the ability to do it. The classical compatibilist then gives a counterfactual account of having an ability. Thus, the classical compatibilist's understanding of PAP (as PAPC) can be derived like so:

(3) You're accountable for x only if you had the ability to not x.

(4) You have the ability to not x only if had you decided to not x, you would have not x-ed.

(5) Therefore, you're accountable for x only if had you decided to not x, you have not x-ed.

An effective argument against the classical compatibilist, then, will be one in which the modality in play is understood as practical possibility.

Chisholm v. Classical Compatibilism: Part I

The classical compatibilist argues that properly understood, the thought that we're accountable for having done something only if we could have done otherwise does not yield the conclusion that if determinism is true, we're accountable for nothing.

According to the classical compatibilist, what we indicate by utterances of "x couldn't have done otherwise" is that x lacked the ability to do otherwise. This, in turn, gets understood as its being false that if x had decided to do otherwise, then would have done otherwise.

Thus, on the classical compatibilist view,

x is accountable for y only if x could have done otherwise [call this PAP]

should be understood as

x is accountable for y only if it is true that had x decided otherwise, x would have done otherwise. [call this PAPC]

As it happens, on this construal, the idea that accountability requires the ability to do otherwise is no barrier to accepting that we're both determined and accountable.

Sadly, as Chisholm argues, it is far from clear that PAP is equivalent to PAPC. The problem is this: it could be true that you would have done otherwise, had you decided to, but false that you could have done otherwise.

His argument goes like this:

(1) Suppose that you couldn't have decided to do anything other than what you did decide to do.

(2) Therefore, you could not have done anything other than what you did do.

(3) But, it might nonetheless be true that you would have done something else had you decided to do something else.

(4) Therefore, PAP is not equivalent to PAPC.