Thank you for the classic definition. Can you agree with me that it immediately falls apart, as a definition? “The possibility to have done otherwise “ is way too frivolous as a philosophical statement. Possibilities are figments of the mind, acted upon to varying results. It’s impossible to define all the possibilities of a given phenomenon so we have to leave that out of the definition for sure. “Otherwise” is also problematic- another figment that we construct from experience.

Why we do things, isn’t because of chemistry. If you chose to, you will change your brain chemistry. Free will is a phenomenon of mind and the pieces and atoms of our selves are not mindful. It’s not that much of a mystery, unless you’re a reductionist mechanistic sort. Which seems to be the fashion around here, but if living in that metaphysical framework makes you happiest, by all means, go ahead.

Just don’t insist it’s the only one. Don’t absolutize your conceptual schemes, man.