Three possibilities come to mind:
Is there an evolutionary purpose?
Does it arise as a consequence of our mental activities, a sort of side effect of our thinking?
Is it given a priori (something we have to think in order to think at all)?
EDIT: Thanks for all the responses! Just one thing I saw come up a few times I’d like to address: a lot of people are asking ‘Why assume this?’ The answer is: it’s purely rhetorical! That said, I’m happy with a well thought-out ‘I dispute the premiss’ answer.
Okay, in other words we need to consider our assumptions and definitions of “Free will” and “Determinism” when answering this question?
I really enjoyed this video on Compatibilism, and the view of Patricia Churchland (around 5:50) where she says we should reframe the question away from “what choices we have” to “how much control do we have”.
Close enough. This topic deserves significant care - of course, in the end, though, people buy into whatever they buy into.
Thanks for the link, I’ll check it out when YouTube is working for me again