I show that the theory of computation implies
that even when our decisions arise from a completely deterministic
decision-making process, the outcomes of that process
are intrinsically unpredictable, even to - especially to -
ourselves. I argue that this intrinsic computational unpredictability
of the decision making process is what give rise to our impression
that we possess free will. Finally, I propose a 'Turing test'
for free will: a decision maker who passes this test will tend
to believe that he, she, or it possesses free will, whether the world
is deterministic or not.