1: If your cousin can demonstrate that ability using somebody else's deck, under experimental conditions that I specify and he is not aware of ahead of time, I will give him a thousand dollars.

2: In the counter-factual case where he accomplishes this, that does not mean that his ability is outside the realm of science (well, probably it means the experiment was flawed, but we'll assume otherwise). There have been a wide range of inexplicable phenomena which are now understood by science. If your cousin's psychic powers are real, then science can study them, and break down the black box to find out what's inside. There are certainly causal arrows there, in any case. If there weren't, we wouldn't know about it.

3: If your strongest evidence that your partner loves you is psychic intuition, you should definitely get a prenup.