How Could Nostradamus Have Seen the Future?

What we really are asking is whether there can be knowledge of the future which is not grounded on observation and memory. If Nostradamus genuinely foresaw events that were to happen in the future — that is to say, if he possessed the power of clairvoyance — what we are saying is that his state of belief was caused directly by something happening in the future, rather than by events preceding the formation of that state of belief. In other words, for his state of belief to be anything other than a lucky guess, a cause would have to occur after its effect.

You don't have to go along with philosopher David Hume's analysis of causation, or his account of belief, in order to find the concept of 'clairvoyance' problematic, on the grounds that we simply cannot understand what it would mean for a cause to occur after its effect. Suppose I discovered that whenever I say 'Humpty Dumpty' three times as my daughter is walking up the driveway towards my house, I receive a letter containing five dollars. But when I fail to say 'Humpty Dumpty' no such letter arrives. Then it looks as though, by some mysterious process, saying 'Humpty Dumpty' three times brings it about that yesterday someone put five dollars in an envelope and sent it to me. Isn't that weird? How could that possibly happen?

One answer would be, 'We just don't know how a cause can occur after its effect, but still we can — for example, in the Humpty Dumpty case — know that it does. I am very unhappy with that answer.

The point is that we seem to understand the idea of a capacity to see the future. The question, which I leave open for discussion, is whether any sense at all can be made of that idea.