by John Allen Paulos

Election Day is just a week or so away and we can be sure that there will be many bogus claims that elections in this or that state or district were rigged. Of course, these claims generally depend on outright lies, not on the counterintuitive subtleties of probability theory, one of which is described here. Stated in terms of a long sequence of coin flips, the surprising bit of mathematics is called the Arcsine law. It focuses on the changing difference between the number of Heads up to a point in the sequence and the number of Tails up to that point.
What might we say about this changing difference? Assuming the coin is fair, we would naturally assume that the difference, the number of Heads minus the number of Tails, would change as the coin flips continue and would sometimes be positive and sometimes be negative. Furthermore we might expect that the difference between the number of Heads and the number of Tails would be positive about half the time and negative about half the time.
We might also conceive of flipping coins as counting the ballots between two evenly matched candidates, Harry and Terri. Since the candidates are, by assumption in a dead heat, we might expect in the ballot counting process that Harry at times will be ahead of Terri and Terri at times will be ahead of Harry. Furthermore, during the counting process we might expect each of the candidates to be ahead about half the time.
Whether expressed in terms of coin flips or votes, this intuition “about half the time” is not correct. What happens is that it’s considerably more likely that either Harry/Heads will be ahead during almost the entire counting/flipping process or that Terri/Tails will be ahead during almost the entire counting/flipping process than it is that Harry/Heads will be ahead about half the time and Terri/Tails about half the time. Read more »




Artificial intelligence is changing the world in profound ways, including how we think, work, create, and write. At 3 Quarks Daily, we believe these developments deserve serious attention, thoughtful criticism, and open-minded experimentation.





It didn’t really surprise me that someone has worked out the mathematical laws I have been reading about of late. It did surprise me that it’s taken me till the ripe old age I’m at now, when the laws have been known for over a century, to find out about them.
Sughra Raza. Dancing On The Esplanade. Boston, August 2026.



Why am I reviewing in Autumn 2026 a book that came out in Spring 2024? Because of what else is happening this Autumn; all the political events that I describe here took place during August and September this year.