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.
There was a relevant post on Lemmy the other day:
The origin and nature of existence is an epistemological black hole that some people like to plug with “a
wizardgod did it”.The sensation of free will is an emergent property of a lack of awareness of the big stuff, the small stuff, the long stuff, and the short stuff.
I like to look at the illusion of free will as if you’re falling down a pit. You can try to flap your arms or swim, and maybe move yourself a little bit, but at the end, you’re still falling down.
Warning, I came up with this while very high one time, lol, but it’s kind of stuck with me:
Consciousness is a 4-dimensional construct living in a 3-dimensional world. What we experience as the passage of time is just our consciousness traveling/falling along the surface of the 4-dimensional plane/shape that defines our existence.
Feel free to poke all the holes you want in that. lol
This is basically a spacetime worldline, which is one of those terms that sounds like scifi technobabble even though it’s an actual concept