It’s an age-old grammar debate: “May I go to the bathroom?” versus “Can I go to the bathroom?” So, which is it? The answer isn’t simple. While the two are relatively interchangeable in conversational speech, there are some traditional English language rules based on formality for when to use "may" or "can." The simplest answer is that “may” is asking for permission, and “can” indicates ability — but let’s dive in a little deeper into the differences.
To understand the “may” versus “can” debate, a look at auxiliary verbs is necessary. Auxiliary verbs, sometimes called helping verbs, are used alongside another verb to show the verb’s tense or to form a question. In addition to “may” and “can,” other words that function as auxiliary verbs include “have,” “be,” “do,” “shall,” “will,” and “must.”
Consider the question “Shall we eat?” — “shall” is the auxiliary verb and “eat” is the main verb. “Shall” can be replaced with other auxiliary verbs, such as “should,” “can,” “may,” and “must." The question still makes sense but would have a different meaning or level of formality.
When to Use “May”
By definition, “may” is used to express permission, as in, “You may go now.” It has been in use since at least the 12th century in Old English, when it originally meant, “to have the ability to.” However, the modern definition leans more toward permission than ability. So, the question, “May I go with them?” (Am I allowed to go with them?) showcases the correct usage of this verb.
When to Use “Can”
“Can” indicates being physically or mentally capable of doing something, as in, “I can play basketball.” So, the correct usage of “can” in a question is, “Can you play basketball?” However, sometime in the 19th century, “can” took on a new usage. A secondary definition of “can” is “to have permission to — used interchangeably with may.”
More Examples of “May” vs “Can”
It’s not wrong to ask your teacher, “Can I go to the bathroom?” but, according to traditional English rules, “can” is still the less formal version of “may.” Depending on the situation and personal preference, “may” is still favored when asking for permission. Let’s look at a few examples for context clues.
- “May I have some water?” vs “Can I have some water?”
Both are technically correct, but at a fancy restaurant or formal event, use “may.” At home, feel free to use either.
- “I may golf.” vs “I can golf.”
When used in a statement, the differences between “may” and “can” are a lot more noticeable. The first sentence means that someone might golf, perhaps if the weather cooperates. The second sentence is suggesting that someone knows how to play the game.
“Shall I” vs “Should I”
As auxiliary verbs, “shall I” is technically synonymous with “should I,” but there are best practices for each. By definition, “shall” expresses what is inevitable or likely to happen in the future. It indicates certainty. “Should” expresses what is probable or expected, but it’s less certain than “shall.” Both “shall I?” and “should I?” can be correct, but it depends on the context of the question. For example, “Shall we dance?” has a different connotation (extending an invitation) than “Should we dance?” (questioning whether it should happen).
“May I ” vs “Might I”
“Might” is generally interchangeable with “may” when used in a question, but “might” is considered more polite. For example, “Might I ask who is calling?” is more polite than, “May I ask who is calling?” Both, however, are correct.
In general, swapping auxiliary verbs won’t make a question incorrect, but it might change its level of formality or its connotation. When in doubt, insert a phrase like “pardon me” or “excuse me” to assure your audience that your intentions are formal or polite.
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