Comment by munk-a

That is a statement that may be true but we've spent a whole lot of time thinking about it and there's still significant disagreement at an academic level, though, with our better understanding of quantum mechanics it has been much more difficult to justify the point that we live in a fully deterministic universe, lately.

And if we reject determinism then definitionally there's arbitrary probability somewhere in the heart of our decision making (though probably in a very minor role compared to established biases).