Caplan’s thought experiment does seem confused to me, so I’m not sure exactly what his position is and I’m not confident that it’s coherent. But his being told of the prediction in advance is a very deliberate feature of the thought experiment, so I don’t think you can make it testable by removing that.
As for whether being owned at RPS should surprise him, or should in general shake the confidence of a free-will libertarian—I can’t imagine anyone having failed to notice that better-than-chance predictions of human behaviour are often possible, so I still don’t see why a direct demonstration of this would threaten their beliefs. Any thoughtful free-will libertarian must have a theory that is (believed to be) compatible with partial predictability.
Caplan’s thought experiment does seem confused to me, so I’m not sure exactly what his position is and I’m not confident that it’s coherent. But his being told of the prediction in advance is a very deliberate feature of the thought experiment, so I don’t think you can make it testable by removing that.
As for whether being owned at RPS should surprise him, or should in general shake the confidence of a free-will libertarian—I can’t imagine anyone having failed to notice that better-than-chance predictions of human behaviour are often possible, so I still don’t see why a direct demonstration of this would threaten their beliefs. Any thoughtful free-will libertarian must have a theory that is (believed to be) compatible with partial predictability.