Q: I still occasionally have to stop and think about the “can” and “may” conundrum. Could you explain the differences once and for all? —Marcus W.
A: This question takes me back to my elementary school days, where my fourth-grade teacher wouldn’t let me be excused to use the restroom unless I asked her for permission correctly. That year my bladder paid a steep price for my grammatical missteps. But I always use the two words correctly now, and I’m hoping that after reading this answer, you will, too.
“Can” and “may” have distinct differences. “Can” expresses the ability to do something, physical or mental. I can lift my daughter over my head. I can add two plus three without a calculator. I can beat our managing editor in a game of Scrabble.
“May,” on the other hand, expresses permission to do something. My mom said I may go to the movies only if I eat all my veggies. May I use the restroom? I may not use the Scrabble example mentioned above per the request of our managing editor who, after fact checking it, found it to be incorrect.
All that being said, the tides of these words have been shifting over the years and, in informal settings, it has become fairly common (and somewhat acceptable) to use “can” when asking for permission. So I wouldn’t call someone out at a dinner party for asking if they “can” use the restroom, but I would definitely change it to “may” if I were editing her novel.