How to Write Right: Might Makes Right

“I wish they may, and I wish they might,” sings Marian the librarian in The Music Man. Marian is using two words, “may” and “might,” in the same way, but they are not always interchangeable. Here's a sentence that highlights a problem with using the two words as synonyms:

If I had known the tickets were free, I may have gone to the concert.

“May” and “might” are both used to express present uncertainty, with very little detectable difference in meaning, but “may have” and “might have” are different. “May have” expresses uncertainty as to whether something happened or not. “Might have” is used to describe a potential road not taken. I may have left the window open when I went out to dinner, but then again maybe I didn’t. I might have gone to law school directly after college, but I didn’t.

So the example above expresses uncertainty where no uncertainty exists. I know whether I went to the concert or not. What it should express is what could have happened under other circumstances, but didn’t in real life. The outcome described is not what definitely would have happened (because even if I had known the tickets were free, I might not have been in the mood to go) but what possibly would have happened:

If I had known the tickets were free, I might have gone to the concert.

Illustration by Andrew Saeger