These examples show that the word "can" gets used in a variety of ways. In (1) we're talking about what Felix is permitted to do. In (2) we're talking about what I have the opportunity to do. In (3) we're talking about what John now has strength enough to do, and speculating about what strength is achievable for him. This shows us that claims of the form "X can do such-and-such" mean a variety of different things. So too with claims like form "It could have happened that Y" and "X can bring it about that Y." There is not just one way to interpret such claims.
Now, is there any sense of "can" according to which determinism entails that you can only do the things you in fact do? Perhaps there is a sense of "can" according to which this follows. If determinism is true, then, given the way the world was before you were born, it was causally determined that you would do the things you in fact do. You "can't" do anything else--in the sense that, given the way the past is, the laws of nature exclude your doing anything else. So in that sense of "can," the things you in fact do are the only things you can do.
But as we saw, the words "can" and "could" can mean many different things. What we need to know is not whether there's a sense of "can" according to which determinism entails that you can only do the things you in fact do. Perhaps there are other senses of "can" which do not have that consequence. What we need to know is not whether there's some sense of "can" which lets us say this, or some sense of "can" which lets us say that. Our task is much harder than that. What we need to do is to somehow identify some senses of "can" that we're independently interested in, and ask whether, with that sense of "can," determinism entails that you can only do the things you in fact do. For example, when we say that being morally responsible for an act entails that you can refrain from performing that act, is that sense of "can" compatible with determinism? This question is not very easy to answer.
Let's begin by considering paradigm cases in which you're not able to act freely, and you don't seem to be morally responsible for your actions. Then we can try to figure out what all such cases have in common.
Suppose your friend is drowning and needs your help--but you can't help him because you're chained to the wall. Or there's a locked door between you and your friend. Or a high wall which you can't scale. In all these cases, you are not able to act freely because there is some external impediment which prevents you from doing what you want to do.
Another sort of case is where you want to help your friend, but you can't reach him in time, because you have a broken leg, or because your legs are paralyzed. These kinds of handicaps can also impair your ability to act freely.
A third sort of case is where you are pulled along by ropes, against your will. In the earlier cases, there were obstacles that prevented you from moving in certain ways. Here an external force is being applied to you which forces you to move in a certain way. In this case, too, you are prevented from doing what you want to do.
A fourth sort of case is where someone holds a pistol to your head and threatens or coerces you into acting a certain way. We have to be careful here. Not every sort of coercion will count as taking away your ability to act freely. If I threaten to give you a "D" in Central Problems unless you carry out a bunch of assassinations for me, and you go ahead and carry out my orders, you can't excuse your actions by saying that I forced you to do it. The threat I held over your head was too weak, compared to the badness of your subsequent actions. Suppose, on the other hand, that I hold a much greater threat over your head. Perhaps I threatened to kill you if you did not comply. And suppose all I make you do is throw eggs at some Professor in another department. In this case, it does seem wrong to hold you responsible for your actions. When we talk about coercion in this class, we'll suppose that we're always dealing with cases of this latter sort, where the threat always does seem to be strong enough to excuse the agent for his or her actions.
In cases of coercion, it also seems to be the case that something (a threat) is preventing you from doing what you want to do. Of course, if a mugger holds a pistol to your head and tells you to hand over your money, there is a sense in which handing over your money is what you want to do. Taking everything into consideration, including what will happen if you don't hand over your money, it seems that handing over your money is the most desirable option. But there's also a sense in which you're being forced to do something you'd rather not do. You don't want to give the mugger your money; he's forcing you, by threat, to do something you wouldn't otherwise choose to do.
So a common element to all of these cases is that you're being forced to do something you don't want to do, or you're being prevented from doing something that you do want to do. So we might say, as a tentative first stab, that:
(C1) You do X freely iff:
- you do X, and
- doing X is what you want and choose to do
There is no obvious reason why the kind of freedom we articulate in (C1) should be incompatible with determinism. The fact that I was causally determined to lecture today does not entail that I don't want to lecture. (I may very well have been causally determined to want to lecture, too.) The fact that I was causally determined to lecture is compatible with my wanting to, and deciding to, lecture today.
So if this is the kind of freedom we're interested in, if it's the kind of freedom which is required for moral responsibility, then freedom does seem to be compatible with determinism, after all.
This account of freedom is sometimes expressed with the slogan "Freedom is opposed to constraint not to necessity." What this means is that the opposite of freedom is not causal "necessity" or determinism. Rather, the opposite of freedom is being constrained to act, that is, not being able to act in the way you want to act, because of a force or threat or chain binding you to the wall. It's not the mere fact that your act is causally determined that makes it unfree. It has to be caused in certain ways, for it to be unfree. It has to be caused in one of the ways we described, that prevent you from acting in the way you want to act. The philosopher A.J. Ayer says:
It is not when my action has any cause at all, but only when it has a special sort of cause, that it is reckoned not to be free. (p. 21)
Well, is this the kind of kind of freedom we're interested in?
Sometimes people suggest that, even if our actions are determined, still, we can find a certain kind of freedom by not struggling against the inevitable. Rather, we should resign ourselves to our circumstances. We're like dogs on a leash being pulled behind a wagon. We can trot along peacefully or we can resist. Either way we'll end up at the same destination. At least if we resign ourselves to our situation and trot along peacefully, we can say we're responsible for our own fate.
Yeah right. I don't know about you, but that doesn't strike me as being a very satisfying sort of "freedom." Yet in the case I described, trotting along peacefully behind the wagon is what you want and choose to do. So really acting freely must involve more than we've articulated in (C1).
The problem with the the dog-behind-the-wagon story is that you're not following the wagon because you want and choose to follow it. You'd be following it no matter what. You have no choice in the matter. Of course, you may have gone through the process of choosing, and decided to follow the wagon. But you have no choice--in the sense that there's no other action which you could perform, instead. If you had chosen to stay in one place, instead, you'd be out of luck. The ropes will pull you along after the wagon whether you want to follow it or not. (See van Inwagen p. 198. There may also be cases where you have a choice but don't make a choice, for example when you act out of automatic habit.)
This suggests that we should add to (C1) something about our having alternative options open to us. We think that, whenever we really do something of our own free will, it has to be the case that we could also have done something else instead. If we had chosen to do something else, there should be no obstacle to our doing it.
What does this mean, to say that you "could have done something else"? The compatibilist understands this as follows. When we say "you could have done something else," he thinks, we mean that if you had chosen to do something else, you would have succeeded in doing something else. Nothing but your choice prevents you from doing the other thing. We call this the compatibilist's analysis of "could have done otherwise." (Sometimes it is called the conditional analysis, instead.) van Inwagen explains this view as follows:
According to this solution, a future is open to an agent if, given that the agent chose that future (chose that path leading away from a fork in the road of time), it would come to pass. Thus it is open to me to stop writing this book and do a little dance because, if I so chose, that's what I'd do. But if Alice is locked in a prison cell, it is not open to her to leave: if she chose to leave, her choice would be ineffective because she would come up against a locked prison door. (p. 188)
In the the dog-behind-the-wagon story, it is not true that you could have done otherwise, in this sense. If you had chosen to stand in one place, you would have been dragged along after the wagon anyway. Nor is it true that you could have done otherwise in our other paradigm cases, involving chains or locked doors or paralyzed limbs. Hence, the compatibilist proposes:
(C2) You do X freely iff:
- you do X, and
- doing X is what you want and choose to do (we still need this, to rule out cases of coercion), and
- if you had chosen to do something other than X, you would have succeeded in doing that other thing
If we accept this account of what it is to do X freely, then once again, being causally determined to do X seems to be compatible with doing X freely. After all, being causally determined to do X does not prevent me from satisfying condition (b). And it does not seem to prevent me from satisfying condition (c), either. It may be causally determined that I would lecture to you right now. But that's because (it was causally determined that) I chose to lecture to you. If the world had gone differently, in such a way that I (was causally determined to) choose to stay home today, instead, then I would be at home right now, instead of standing here lecturing to you. So I can satisfy condition (c) of this proposal, even though I am causally determined to act in the way I do.