In the classic Foundation series which is a science fiction series of books by Isaac Asimov there is the old and dying Empire and the young and rising Foundation. The premise of the series is that the mathematician Hari Seldon spent his life developing a branch of mathematics known as psychohistory, a concept of mathematical sociology. Using the laws of mass action, it can predict the future, but only on a large scale. Wikipedia Link
At one point in history the Empire would be aware of the Foundation and still capable of destroying it, but this would never happen because there could only be three situations.
1) If there was a weak general the Empire could never conquer the Foundation.
2) If there was a strong general and a weak emperor the strong general would return (like Caesar) to become the new emperor.
3) If there was a strong general and a strong emperor the emperor would recall the general because he would be too much of a threat.
This election has a similar feature.
The very tightening of the race prevents Trump from winning. There is a bevy of voters who are not jazzed by Clinton but are petrified by a Trump presidency. Once polls start to show that it’s close, they will decide to vote for Clinton or say so in a poll. When the lead expands, they get more complacent and disaffected by Clinton’s flaws.
Nate Silver says I should be nervous about the election. Here’s why I’m not too nervous.