Today's English lesson

From the American Heritage Book of English Usage:

Mother, May I?
Yes, You Can!


can and may

Can I go to the bathroom?

Nearly every child has asked this question only to be corrected with:

You mean, May I go to the bathroom?

Generations of teachers have insisted that can should be used only to express the capacity to do something and that may must be used to express permission. But let’s face it, children don’t use can to ask permission out of a desire to be stubbornly perverse. They have learned it as an idiomatic expression from adults:

If you finish your spaghetti, you can have dessert.

After you clean your room, you can go outside and play.

In these and similar spoken uses, can is perfectly acceptable. This is especially true for negative questions such as:

Can’t I have the car tonight?

probably because using mayn’t instead of can’t sounds unnatural. Nevertheless, in more formal usage the distinction between can and may still has many adherents. Only 21 percent of the Usage Panel accepts can instead of may in the sentence:

Can I take another week to submit the application?

May is common in official announcements:

Students may pick up the application forms tomorrow.

The increased formality of may sometimes highlights the role of the speaker in giving permission.

You may leave the room when you’re finished

implies that permission is given by the speaker.

You can leave the room when you’re finished

implies that permission is part of a rule or policy rather than a decision on the part of the speaker.

can showing possibility. Like may, can can also be used to indicate what is possible:

It may rain this afternoon.

Bone spurs can be very painful.

In this use, both can and may often have personal subjects:

You may be right.
You may see him at the concert.
From the mountaintop you can see the ocean on a clear day.
Even an experienced driver can get lost in this town.