In any event, the way he explains his position regarding free will in this interview extract that recently appeared on Salon is, in my opinion, very convincing.
It's good to see a professional philosopher type explaining well a line of argument that, I always felt during idle showertime thoughts on the topic, made a lot of common sense. Here are some key sections:
NW: The classic description of the problem is this: ‘If we can explain every action through a series of causal precedents, there is no space for free will.’ What’s wrong with that description?
DD: It’s completely wrong. There’s plenty of space for free will: determinism and free will are not incompatible at all.
The problem is that philosophers have a very simplistic idea of causation. They think that if you give the lowest-level atomic explanation, then you have given a complete account of the causation: that’s all the causation there is. In fact, that isn’t even causation in an interesting sense.
NW: How is that simplistic? After all , at the level of billiard balls on a table, one ball hits another one and it causes the second one to move. Neither ball has any choice about whether it moved; their paths were determined physically.
DD: The problem with that is that it ignores all of the higher-level forms of causation which are just as real and just as important. Suppose you had a complete atom-by-atom history of every giraffe that ever lived, and every giraffe ancestor that ever lived. You wouldn’t have an answer to the question of why they have long necks. There is indeed a causal explanation, but it’s lost in those details. You have to go to a different level in order to explain why the giraffe developed its long neck. That’s the notion of causation that matters for free will.
NW: So that’s an evolutionary hypothesis about giraffes’ necks. H ow does it shed any light on the free will debate?
DD: If I want to know why you pulled the trigger, I won’t learn that by having an atom-by-atom account of what went on in your brain. I’d have to go to a higher level: I’d have to go to the intentional stance in psychology Here’s a very simple analogy: you’ve got a hand calculator and you put in a number, and it gives the answer 3.333333E. Why did it do that? Well, if you tap in ten divided by three, and the answer is an infinite continuing decimal, the calculator gives an ‘E’.
Now, if you want to understand which cases this will happen to, don’t examine each and every individual transistor: use arithmetic. Arithmetic tells you which set of cases will give you an ‘E’. Don’t think that you can answer that question by electronics. That’s the wrong level. The same is true with playing computer chess. Why did the computer move its bishop? Because otherwise its queen would have been captured. That’s the level at which you answer that question.