providing the margin

fox is doing a piece on how every vote counts. don't think your vote doesn't matter! because one time one vote decided an election! i think it was a california congressional race in 1948. remember hayes/tilden? well that was almost like that; really it almost could have been like that. or remember that kevin costner movie? now this seems to imply a principle: that the extent to which your vote matters is equal to the probability that the margin of victory for the candidate for whom you vote is exactly 1. of course even there it would be silly to say that your vote provided the margin, since x millions could say the same; your vote even in this scenario provides xmillionth of the margin. but obviously you'll need a better argument because you've just exactly confirmed my point.