That's how I see it too. Determinism for human action is very popular among science enthusiasts because we've decided that determinism elsewhere in science is

That's how I see it too. Determinism for human action is very popular among science enthusiasts because we've decided that determinism elsewhere in science is true, and since our brains is part of the universe then it must also be deterministic. But we only perceive determinism insofar as we only measure what we're able to measure. Then you arrive at quantum probabilities, and it seems to me the multiverse theory is as scientific as believing quantum particles have free will.