Free will: the horse and the engine

I'm planning to do a few posts on the problem of free will. It's a daunting topic to even begin to talk about, partly because it touches on everything you do in your life, and also because it's one of those philosophy problems that's been debated for thousands of years with no consensus; what are the odds that your attempt to solve it is going to be convincing?

One of my professors in law school made this comment to introduce a case we were going to study that day: "When the Supreme Court granted cert, most people agreed that this was a very easy case. They just couldn't agree on whether it was an easy reversal or any easy affirmance" (the two possible outcomes). The free will problem is like that. Everyone thinks the answer is so easy and obvious it's hardly worth talking about. The problem is, people have that feeling equally strongly on both sides (or should I say on all three sides?) ... so maybe it's not so simple.

Before I get into the substance of the debate, I want to share a passage that's not explicitly about free will, though the author later connects it to free will. This story dates back to the 19th century, when a new railway had been built in Germany:

When it reached the village of a certain enlightened pastor, he took his people to where a locomotive engine was standing, and in the clearest words explained of what parts it consisted and how it worked. He was much pleased by their eager nods of intelligence as he proceeded.

But on his finishing they said: "Yes, yes, Herr Pastor, but there's a horse inside, isn't there?" ...

It is ... a great effort to think of all the parts working together to produce the simple result that the engine glides down the track. It is easy to think of a horse inside doing all the work. A horse is a familiar totality that does familiar things.*

I find it interesting that he uses this anecdote to leverage his "compatibilist" position on free will. By "compatibilist," I mean he believes we have free will, but it coexists with determinism. But you could just as well use the horse anecdote as a criticism of philosophers who aren't comfortable introducing free will into our picture of the world unless determinism remains intact. After all, for us in the scientific age, the idea of a deterministic machine is a "familiar totality that does familiar things."

* This is from an essay by R.E. Hobert (a pseudonym for Dickinson S. Miller, who I've never heard of either) called "Free Will as Involving Determination and Inconceivable Without It," from the anthology Metaphysics: The Big Questions, and originally appearing in Mind in 1934; the anecdote in turn comes from Friedrich Paulsen. I've added line breaks for readability.