What could you do for a million dollars?

A week ago I asked my brother if he thought he could make himself to believe that a given ordinary object were in a sealed box simply upon my asking him to, and he said he could: he would trust my testimony. So, if I said "Jeff, believe that there are scissors in this box", he thinks he could believe it, just like that. So he claims.

Then I asked him if he thought he could make himself to believe, for a million-dollar reward, that a given ordinary object were in a box, after my having opened the box, clearly showing him that nothing whatsoever was in the box, and then sealing the box in his presence. A million dollars to believe that scissors are in a box he had plainly seen moments before to be empty. He thought he could do it.

He said he would have to really lie to himself--deceive himself into discrediting the evidence that I'd just presented him with.

Then I asked, "what if you had to shake the box up and down?" That got him.