In this lesson we are looking at the use of ‘should’ and ‘ought to’ for obligation and probability. As with other modals the meaning given to the verb depends on the context it is used in.
When we want to talk about obligation we are talking about the right thing to do:
You should/ought to finish your homework before you watch TV.
You shouldn’t/ought not to leave lights on when you leave the room.
Should/ought to are also used to say what is the best thing to do or to give recommendations:
You should/ought to walk to work.
The weather in Malta is perfect. You should/ought to come over for a holiday.
With question forms ‘should’ is used more than ‘ought to’:
Should I invite our neighbours to the party?
Who should I ask if I have a problem?
‘Ought to’ can be used in questions but this is now considered too formal or archaic.
Should/ought to + have + past participle can be used to talk about something that didn’t happen that the speaker regrets:
I should have/ought to have invited the neighbours to the party. They were so offended.
‘Should’ and ‘ought to’ can be used to talk about something that is probable or that it is expected to happen or that it is true:
We should/ought to be finished by this afternoon.
You should/ought to receive an answer by next week.
Should/ought to + have + past participle are used to talk about something that was expected to happen in the past.
We should/ought to have finished by the afternoon yesterday.
You should/ought to have received an answer by now.
This structure can be used to express a future probability too.
‘Should’ and ‘ought to’ are not normally used to express a negative probability but a positive one.
He should/ought to get the promotion. NOT He should not get/ ought not to get the promotion.
Part 1 - Modals A – May/Might (Permission, Possibility)
Part 2 - Modals B – must/have to (Necessity – Deduction)
Lesson by Tristan, English teacher at EC Malta English school
