When to Use 'May' and 'Can' in English

Language evolves, and so do the usages of certain words. In school, one of the clear-cut distinctions between may and can was drilled into us: may requests permission, while can is about ability. However, the distinction is not as rigidly observed in modern day-to-day conversations as it once was. In reality, can is often used in a more informal context, and thus appears more frequently in spoken language compared to may.

Formal vs. Informal Usage

May is a more formal word, often employed to politely seek permission or express a gentler possibility. If you are hesitant to be seen as informal or to possibly face criticism, using may can be a safer choice. On the other hand, can has become the more colloquial verb of choice, especially when it comes to discussing ability. Both can and may can still be used interchangeably, depending on personal preference or the desired tone.

Semantic Differences

May and can share the function of modal verbs, indicating the probability or likelihood of an event. However, there are subtle differences in their usage and implications.

May vs. Can: A Case Study

May is used to express weaker possibilities, where the likelihood of something happening is less certain. For example:

Schools may open this week.

In contrast, can is used to assert a stronger possibility, indicating a higher degree of certainty or a demonstrated ability. For example:

He can dance.

The best example to illustrate the usage of may and can can be seen in the following scenario:

Example Scenario

- May I come in? - This is a polite request for permission to enter.

- Can I come in? - This is a question about your own ability to enter, not necessarily a request for permission.

In this context, May I come in? would be the most appropriate choice.

Probability vs. Possibility

When discussing outcomes, the choice between can be and may be subtly changes the meaning:

Can Be vs. May Be

- Can be suggests that an outcome is possible, potentially within a range of options. For example:

At the end of this year I could can weigh less than 130 pounds

- May be, on the other hand, is related to probability, indicating a higher likelihood. For example:

At the end of this year I may weigh less than 165.

In this context, the likelihood is greater, but still not a certainty.

Practical Example

The best way to understand the practical implications is through a concrete example:

Example Scenario

Florence can swim from England to France, but for her next vacation she may take a plane.

Here, Florence can swim to France by various means: she can fly, drive, take a boat, a plane, a car, or even swim. However, realistically, she may take a car, plane, or sail.

Final thought: While can indicates an ability and a theoretical possibility, may points toward a more probable outcome based on current circumstances.