> If you’re arguing from a context in which “you” isn’t defined, then the notion of “will” — free or otherwise — is irrelevant.

If someone is arguing that we do have free will, surely “there is no will” is a valid way to counter.

> Of course they obey physical laws; the distinction is the series of reactions that could occur but don’t.

What do you mean “could have occurred”? If reality proceeds according to physical laws, only the things that did happen could have happened. If other things could have happened, they would have happened instead.

You could have acted differently to the way you did yesterday, sure. And the moon could be made of cheese.

> the ability to chart multiple courses of viable action and selecting one

But you’re not. You just have the perception that you are.

> Your argument seems to be that the chemical composition of my brain prevents me from doing anything but imagining those sentences,

Yes. The current composition as a result of all the interactions your constituent particles have had during your life.

> but my perception is that I could go on at length if I chose to do so

Our perception is not relevant to the issue.