“”Why do I think I have free will?” “Because I do,” is a perfectly good answer (assuming free will).”
Disagree. Notice how this answer is only ‘good’ assuming free will. But our assumption of free will is exactly what we are seeking to understand the cause of. We can assume free will is correct and that this is adequate to justify our answer (‘because I do’), but then we have only re-posited the assumption in the consequent.
A useful trick to optimize the accuracy of your priors when considering examples is to semantically disentangle each example in the form of a conjunctive statement. This allows you to avoid the conjunction fallacy, where an example, verbally stated, holds only when many smaller statements conjoined by an and or several them are all true.
By doing this, we can also compare examples rather than treating them as all having the same probability value.