In a recent talk at MIT, Umesh Vazirani appealed to the famous Birthday Paradox to say that two random subsets of {1,…,N}, each of size o(√N), probably wouldn’t intersect each other. Of course we all understood what he meant, but it occurred to me that Umesh was actually appealing to the Birthday Unparadox: “If you put three people in a room, chances are no two of them will have the same birthday.”

Once I realized that, I started seeing unparadoxes everywhere I looked:

The Banach-Tarski Unparadox: If you cut an orange into five pieces using a standard knife, then put them back together, the result will have exactly the same volume as the original orange.

Braess’ Unparadox: If you add an extra lane to a highway, one possible result will be to decrease congestion.

Hempel’s Unparadox: If you observe a bunch of ravens and find that all of them are black, this might increase your likelihood for the statement “All ravens are black.”

Russell’s Unparadox: The set of all sets that contain themselves as a member, might or might not contain itself as a member (either way is fine).

In the spirit of my highly-successful Best Umeshism and Best Anthropicism contests (remember those?), I now open the floor to you: come up with the best unparadox! The winner will receive absolutely nothing. (If you have to ask what the point is, this contest isn’t for you.)