May Versus Might

Grammar Girl here.

Thanks, Elizabeth! The difference between may and might is subtle. They both indicate that something is possible, but something that may happen is more likely than something that might happen. So you may go to a party if Matt Damon invites you, but you might go to a party if your least favorite cousin invites you.

A Mighty Stretch

I remember the difference by thinking that I should use might when something is a mighty stretch. Imagine something you'd almost never do, and then imagine someone inviting you to do it. For me, it's white-water rafting. The idea terrifies me. So if someone (such as my former employer) asked me to go on a corporate bonding white-water rafting trip, it's unlikely I would go, but I could be convinced if I thought my job depended on it. But it would be a mighty stretch. So I'd say something like, "Yeah, I might go; and pigs might fly, too."

So imagine whatever it is you'd be reluctant to do but wouldn't completely rule out, and then imagine yourself saying in a nice, sarcastic voice, "Yeah, I might." And that should help you remember to use might when the outcome is uncertain or unlikely and to use may when something is more likely to happen, such as attending a nice, safe company lunch where helmets and life vests aren't required.

You might clean your room, but you may call your friend later. You might climb Mt. Everest someday, but you may go hiking in the foothills next weekend.

Might Is the Past Tense of May

There are two exceptions to this rule.

First, might is the past tense of may. So you have to use might when you are referring to the past. For example, even if it's likely that Squiggly went to a party last night, Aardvark shouldn't say, “Squiggly may have gone to the party’; he should say, “Squiggly might have gone to the party.”

The second exception is a gray area. When you're talking about something not happening, it can be better to use might because people could think you're talking about permission if you use may. This is clearer with an example. If you aren't sure whether you'll go to the party, and you say, "We may not go to the party," it can be misinterpreted to mean you don't have permission to go to the party, particularly in writing, where voice inflections don't help guide the meaning. But if you say, "We might not go to the party," then your meaning is clear. It's the safer bet.

So remember to use may when the outcome is likely and might when the outcome is less likely or uncertain. But also remember that you use might for everything in the past tense. Also, it's OK to use might when you're writing about negative outcomes, even if they're likely outcomes, if using may would make people think you were talking about having permission.

Modals

Finally, here's a bit of grammar terminology. May and might are both called modals, as are words such as would, should, and could. Modals are helping verbs that tell you more about the mood or attitude of the action verb. For example, you can tell that someone has a different attitude toward a party depending on the modal used. There's a big difference between I may go, I should go, and I would go.

Web Bonus: List of Common Modals

Garner, B. Garner's Modern American Usage. Oxford: Oxford University Press. 2003, p. 513.

may. Dictionary.com. Dictionary.com Unabridged (v 1.1). Random House, Inc. http://dictionary.reference.com/browse/may (accessed March 9, 2008).

may. Merriam-Webster Online Dictionary. http://www.merriam-webster.com/dictionary/may (accessed March 9,2008).

Merriam-Webster's Dictionary of English Usage. Springfield: Merriam-Webster, 1994, p. 627.

"Some Common Solecisms,”The Economist.com Style Guide

Strumpf, M. and Douglas, A. The Grammar Bible. New York: Henry Holt and Company, 2004,  p. 77.