We all understand fear and love and curiosity well enough that we can make rudimentary predictions about them. If I point a gun at someone they will experience fear and respond with fight or flight. If I spend a lot of time with someone and certain compatibility conditions are met, we will experience love and respond with caring behaviors. If I show someone something that they don't understand fully but that has properties that interest them, they'll likely experience curiosity and respond with questions and exploration.

Someone who studies these things (a psychologist or neurologist) could make even more sophisticated predictions.

We may not have a complete low-level electrochemical model of these phenomenon, but we have a good enough model to make some predictions. But if anything, one of the most salient criticisms of free will is that it doesn't allow us to model and make predictions--in fact, it eschews predictions altogether.

> Free will is the sensation of being in a brain that models counterfactuals

No. Free will is the ability to make a choice not completely dependent on history.

That depends on the person defining it. Why can't it be the outcome my brain has determined for me to take which I subjectively understand as a self-chosen action? That may well depend on my history--my emotions, memories and all the things that shape me--but those are more reasons than constraints.

Isn't that like saying I want to fly, so I don't have free will if I can't?

Would flipping a coin count?

If you respond, "No, because the particles that make up the coin and the muscles that drive my thumbnail have a history that determines the outcome," then how about a slight variation? "I can't decide what to do. I have no idea what time it is, so if the minute digit on my clock is odd, I'll do X, otherwise I'll do Y."

Here I've explicitly refrained from using either a source of randomness or anything else with its own history to determine my fate. The decision to consult the clock might have been an act of free will on my part, but the outcome certainly wasn't.

I don't consider that free will then, that would just be "not completely" free will. If it's not dependent on a history, what would be the directive that effects the choice? To me, the notion of free will just defeats the ubiquitous cause-effect nature in everyday life and observance. What would be the nature of the effector that makes the "free" choice then?

I don't see why anyone should accept a useless definition as a correct one.

Nobody would argue that they had free will if they didn't feel like they had free will. Nobody is positing baseless metaphysical nonsense without some reverence in their actual experiences. If you want to usefully discuss free will, you have to account for the sensation of free will, not just some abstract model that you've merely assembled grammatical statements from.