Learn English – Are “might” and “should” past tenses of “may” and “shall”, respectively


According to the dictionary definitions (e.g. in Merriam-Webster) , "should" is the past of "shall" and "might" is the past of "may":

But are these modal verbs really used as such? I know they are frequently used with other meanings (as confirmed by their other definitions in the dictionary), but my question is if they are really used with their original meaning of past tense for "shall" and "may".

I give two examples below. Do the present and past versions have the exact same meaning (except for the tense, of course)?


Present: When he is at school, he may not go to the bathroom without asking for permission.

Past: When he was at school, he might not go to the bathroom without asking for permission.


Present: He thinks that they shall go the restaurant.

Past: He thought that they should go the restaurant.

Best Answer

Both of the past-tense examples sound somewhat archaic, but that is to some extent because the use of shall in the present-tense sentences does also, imo. (The use of present-tense may in the second sentence sounds formal, but not archaic.)

Probably the last person I heard use might and should with these specific meanings was my grandmother, who learned English as a foreign language about 100 years ago (literally). If your questions is whether you should :-) use the words with these meanings, I would say no, as it will simply be confusing. To convey the past-tense sense of these, you might have to come up with workarounds:

When he was at school, he was not allowed to go to the bathroom ...

He thought that they would go to the restaurant.

Hmm, that second one is tricky, but it's the result of substituting the non-archaic will for shall in the present tense.