Superstition – the willingness to believe based on factors other than those normal individuals would find relevant – is an ailment suffered by Don, an up and coming office manager. At first Don is just influenced by his superstition. He is moved to get real evidence – a call to his office – to confirm a suggestion made by his “seer” – a napkin holder that, for a penny “answers” yes and no questions. When the seer’s prediction is confirmed, Don buys in whole-hog, and becomes immobilized by the seer – who tells him that leaving the dinner before 3 p.m. may be dangerous to his health. Then at 3 p.m., attempting to defy the predictions of the seer, another prediction comes true, and Don is hooked.
Pat asks Don how the “gizmo” predicted the future. This suggests that if something can predict the future, then there is an explanation – a mechanism or causal explanation that is responsible for the correctness of the prediction. But ultimately she drops any attempt to convince Don that his beliefs are not justified. A different strategy – a different kind of argument – is ultimately effective.
What is Pat’s argument? She argues that the belief that the seer can predict the future is itself a cause – and a “bad” cause – of Don’s behavior. Beliefs can be causes, and believing that a napkin holder can predict your future – even if it is possible that it can – is a dangerous thing. This is a significant observation for the determinist and the compatibilist. Although it looks like Pat is saying that the buying into determinism would be bad for one’s mental health, she’s really just saying that if determinism were true and if one also had access to the predictions one could make if one knew all of the initial conditions and all of the relevant causal laws in any situation, then that would be a bad thing. To put it positively: It is important that we have the sense that we are free, whether we are or not.
Notice that Pat’s argument doesn’t depend on positing the truth of determinism. She’s worried about any device that is taken to predict the future, and that could be a complete science, a mystic seer or a direct line to God. Again, to say that events are “predetermined” or “known in advance” is different from saying that every event is determined. Events can be causally determined without being known in advance (though they would be knowable). And events could be known in advance (by a god or a seer or a napkin holder) without those events being (causally) determined.