When you are faced with an unanswerable question—a question to which it seems impossible to even imagine an answer—there is a simple trick which can turn the question solvable.

Compare:

"Why do I have free will?"

"Why do I think I have free will?"

The nice thing about the second question is that it is guaranteed to have a real answer, whether or not there is any such thing as free will. Asking "Why do I have free will?" or "Do I have free will?" sends you off thinking about tiny details of the laws of physics, so distant from the macroscopic level that you couldn't begin to see them with the naked eye. And you're asking "Why is X the case?" where X may not be coherent, let alone the case.

"Why do I think I have free will?", in contrast, is guaranteed answerable. You do, in fact, believe you have free will. This belief seems far more solid and graspable than the ephemerality of free will. And there is, in fact, some nice solid chain of cognitive cause and effect leading up to this belief.

If you've already outgrown free will, choose one of these substitutes:

"Why does time move forward instead of backward?" versus "Why do I think time moves forward instead of backward?"

"Why was I born as myself rather than someone else?" versus "Why do I think I was born as myself rather than someone else?"

"Why am I conscious?" versus "Why do I think I'm conscious?"

"Why does reality exist?" versus "Why do I think reality exists?"

The beauty of this method is that it works whether or not the question is confused. As I type this, I am wearing socks. I could ask "Why am I wearing socks?" or "Why do I believe I'm wearing socks?" Let's say I ask the second question. Tracing back the chain of causality, I find:

I believe I'm wearing socks, because I can see socks on my feet.

I see socks on my feet, because my retina is sending sock signals to my visual cortex.

My retina is sending sock signals, because sock-shaped light is impinging on my retina.

Sock-shaped light impinges on my retina, because it reflects from the socks I'm wearing.

It reflects from the socks I'm wearing, because I'm wearing socks.

I'm wearing socks because I put them on.

I put socks on because I believed that otherwise my feet would get cold.

&c.

Tracing back the chain of causality, step by step, I discover that my belief that I'm wearing socks is fully explained by the fact that I'm wearing socks. This is right and proper, as you cannot gain information about something without interacting with it.

On the other hand, if I see a mirage of a lake in a desert, the correct causal explanation of my vision does not involve the fact of any actual lake in the desert. In this case, my belief in the lake is not just explained, but explained away.

But either way, the belief itself is a real phenomenon taking place in the real universe—psychological events are events—and its causal history can be traced back.

"Why is there a lake in the middle of the desert?" may fail if there is no lake to be explained. But "Why do I perceive a lake in the middle of the desert?" always has a causal explanation, one way or the other.

Perhaps someone will see an opportunity to be clever, and say: "Okay. I believe in free will because I have free will. There, I'm done." Of course it's not that easy.

My perception of socks on my feet, is an event in the visual cortex. The workings of the visual cortex can be investigated by cognitive science, should they be confusing.

My retina receiving light is not a mystical sensing procedure, a magical sock detector that lights in the presence of socks for no explicable reason; there are mechanisms that can be understood in terms of biology. The photons entering the retina can be understood in terms of optics. The shoe's surface reflectance can be understood in terms of electromagnetism and chemistry. My feet getting cold can be understood in terms of thermodynamics.

So it's not as easy as saying, "I believe I have free will because I have it—there, I'm done!" You have to be able to break the causal chain into smaller steps, and explain the steps in terms of elements not themselves confusing.

The mechanical interaction of my retina with my socks is quite clear, and can be described in terms of non-confusing components like photons and electrons. Where's the free-will-sensor in your brain, and how does it detect the presence or absence of free will? How does the sensor interact with the sensed event, and what are the mechanical details of the interaction?

If your belief does derive from valid observation of a real phenomenon, we will eventually reach that fact, if we start tracing the causal chain backward from your belief.

If what you are really seeing is your own confusion, tracing back the chain of causality will find an algorithm that runs skew to reality.

Either way, the question is guaranteed to have an answer. You even have a nice, concrete place to begin tracing—your belief, sitting there solidly in your mind.

Cognitive science may not seem so lofty and glorious as metaphysics. But at least questions of cognitive science are solvable. Finding an answer may not be easy, but at least an answer exists.

Oh, and also: the idea that cognitive science is not so lofty and glorious as metaphysics is simply wrong. Some readers are beginning to notice this, I hope.