I’m not an atheist but my theism is not located OUTSIDE of this discussion but squarely WITHIN it. (In other words no miracles and no references to God).
Causality is one way of looking at a sequence of events and explaining “why something occurred”.
Intentionality is a different way of looking at them, and produces a different explanation.
I find both useful, in different contexts. So far we’re not talking about absolute overarching truths here.
Arguments against free will assert the absolute overarching supremacy of determinism and causality. “You wrote this post * because* neurochemicals in your finger-muscles caused your fingers to strike the keyboard keys in this sequence”. “You wrote this post * because* you were socialized into a culture that inculcated into you certain beliefs about free will, and when stimulated with the question du jour, you spouted forth the set of beliefs with which you’d been programmed”. “You wrote this post because everything is a chain of cause-and-effect and prior events are the reason that any current event is taking place”. These are all causal, or deterministic arguments and there is no reference to intentionality, no assertion that they were written “of the poster’s own free will”.
Intentionality arguments assume an active consciousness made choices and the choices are why the action took place. “You wrote this post because you wanted to express your opinion on the topic of free will, and to contradict people who were being Wrong on the Internet”. “You wrote this post because you consider ‘free will’ arguments to be proxies for arguments about the soul or the appropriateness of holding people responsible for their actions, and this board is devoted to skepticism”.
Intentionality, or “free will”, arguments, rarely assert the absolute overarching supremacy of intentionality. That is, you don’t commonly encounter arguments to the effect that “The galaxies spin around their center of gravity and assume a spiral shape because they like to twirl” or “The rocky mountain chain thrust upwards because it feels glorious to rise into the sky”. So most of the action takes place around whether intentions, desires, etc, explain anything or can (and should) be discarded from our considerations as irrelevant and silly.
I don’t actually like the term “free will” (because it is too tied up in long-ago arguments that someone else made) but there is intentionality; it is true that things occur because some consciousness wanted them to, and untrue that everything is simply a chain of prior events causing current events in a perpetual cause-and-effect chain. The exact nature and location of that consciousness is not simple, but not because I’m about to wave a “God” clause at you, but rather because we individual human folks are not the separate individuals we (at least in our current culture) tend to think we are, which has ramifications for where the consciousness is actually located.