In a previous posting I explained that there are lots of people who think it’s obvious that freedom can’t exist in a deterministic universe, and that this position is known as incompatibilism.
Incompatibilists believe that if everything that happens is caused by prior events then nobody is ever free. Choices, after all, are events—they happen. So, if everything that happens is caused by prior events, this includes all of our choices. And it’s just a short step from here to the idea that if determinism is true, then nobody really makes any choices at all. We’re nothing but marionettes whose strings are pulled by the inexorable forces of nature.
It’s worthwhile to consider why anyone would hold this view. A common pattern of reasoning goes like this. Choosers—that is, real choosers--are responsible for their own decisions. Their decisions are, so to speak, entirely up to them. But if determinism is true, then all of our decisions are just links in a chain of causes and effects for which we are not responsible and over which we have no control.
At this point, the argument bifurcates. Some folks (called 'hard determinists') accept that determinism is true and conclude from this that freedom is at best an illusion. Others, called libertarians, insist that determinism is false and that we are able to make radically free choices that are not fixed by prior causes. We scrutinized hard determinism last time. Now it’s the libertarians’ turn.
Here’s a popular argument for libertarianism crafted by the American philosopher Peter van Inwagen. It’s one that many people find persuasive.
(1) If determinism is true, then everything that happens—including every choice that everyone makes—is a consequence of the state of the universe at some arbitrary time in the distant past (say five gazillion years ago) in conjunction with the laws of physics. In other words, the whole future trajectory of the universe is a consequence of just those laws operating in just those conditions.
(2) If x causes y, and it’s impossible for anyone to do anything about x, and it’s impossible for anyone to do anything about x causing y, then it’s impossible for anyone to do anything about y.
(3) Nobody can do anything about the state of the universe five gazillion years ago, right? And nobody can do anything about the laws of nature—they just are as they are. So if everything that happens is a function of these two factors that nobody can do anything about, then it follows that nobody can do anything about anything.
(4) But that’s absurd! Here you are, reading this article. You can do something about that: you can choose to stop reading. What you do right now is up to you.
(5) That shows that determinism is false.
If you are moved by this argument, I urge you to think again. Just look at the punch line! The fourth premise entails (for example) that you could choose to stop reading this blog at any time, and the the conclusion states that this fact shows that determinism is false. But even the most obdurate determinist will accept that you can stop reading this blog at any time! The issue isn’t whether you can stop reading. That’s a red herring. It’s whether your decision to stop reading is caused by prior events.
The libertarian needs to make the case that your decision to stop reading (or anything else, for that matter) is not caused by prior events. Let me explain why this claim is irremediably problematic.
Consider any choice that you made in the past—say, your choice to start reading this blog posting. According to the libertarian, if God rolled back time to the point just before you made that decision, it would be open to you to make an entirely different choice. Now, you might think, “Of course it would be! That’s a no-brainer!” But if that’s your view, you need to think about the example a bit more carefully. If God re-wound the video of time to that very point, the entire universe, right down to the smallest detail, would be exactly the same as it was the first time around. All of your neurons would be in exactly the same state of activation that they were when you first decided to read this blog, and you would be in exactly the same mental state that you were then—with precisely the same beliefs, desires, thoughts, and perceptions.
Bearing all this in mind, does it still seem plausible to you that you could have chosen differently? Think about it. If you insist that you could have chosen differently while in exactly the same mental state that you were in the first time around, then you are tacitly admitting that your mental states—your beliefs, desires, values, interpretations of the world, and so on—are irrelevant to the choices that you make.
Now that’s crazy!
We’re not finished with libertarianism yet, because there is another powerful objection to it known as the intelligibility problem. It’s an objection that shows why libertarians can’t turn to quantum mechanics to defend their version of free will. I’ll walk you through it in my next posting on the free will problem.