Must versus Have to

The modal grammar quiz is over. Actually, the students did really well on this quiz, but there is still a bit of confusion over some of the subtleties of using modals.

The first kinds of modals we looked at were modals of necessity. Although in essence “must” and “have to” mean the same thing, I noticed that sometimes must doesn’t really work in a sentence, and “have to” is better. There was a question similar to this on the quiz in which the students had to choose between “must” and “have to”:

Murray: I was surprised to see you taking the C-Train this morning. Is your car still not working?
Scott: Can you believe it? It’s still not working. I __________ take it to Canadian Tire to get it checked out, but I never seem to find time.

In the blank, a lot of student put in the word “must” so that the sentence reads:

I must take it to Canadian Tire to get it checked out, but I never seem to find time.

Although, must and have to both indicate necessity. In this case it doesn’t sound right. I think this is because “must” is a bit stronger than “have to”. “Must” really indicates the importance of the act. If you use the word “must”, you are really stressing how much you need to do something. It is absolute urgent and necessary to do it. However, in this sentence, the speaker goes on to say “but I never seem to find time.” If getting the car checked out was really urgent (i.e. “must”), then the speaker wouldn’t have said “but I never seem to find time”. As a result, I think that “have to” is the better choice.