Can, may and might

The words can, may and might all have to do with the possibility of something happening in the future, and the first two can also be used to indicate that permission is being granted for something to happen. But what determines when each of these should and should not be used?

Here are three sentences:

I can go to London
I may go to London
I might go to London

Do they mean exactly the same? Not quite!
The first could mean that it is physically possible for me to go – I have bought a train ticket, for example – whereas the second implies that, although the possibility is there, there is a chance that I won’t go – I could change my mind, for example. Can is therefore more positive than may. The third is nearly identical in meaning to the second, on the assumption that we are only talking about the possibility or probability of going, although may is a more positive word to use in this context.

However, the same words would also suffice to imply that permission has been granted for the trip – in the case of can and may, but not might. In terms of permission granting, there is no real difference between can and may.

There can therefore be confusion as to what is meant in a statement such as: You can open the box. Does this mean that you are physically capable of unlocking it and lifting the lid, or have you been given permission to do so? It could be very important to make this clear, because either interpretation is possible. 

If using the past tense, might does what may does in the present and future tenses: I may go to London tomorrow but I might have gone yesterday. 

When subtle shades of meaning are involved, it is vital to get things like this right! (It is also worth pointing out that can and might have other, completely different, meanings in English, and May is the name of a month. As if this little matter was not complicated enough as it stood!)


© John Welford