Ought to is a very useful verb which unfortunately is very often forgotten. Here, we will look at whether there are any
differences between ought to and should, and whether they be used interchangeably.
1. Expressing expectation
Ought to, should and also expect to can be used interchangeably to express expectation: the person speaking or writing
thinks or supposes that this will be the case.
For example:
I'm in a meeting at the moment. We should / ought to / expect to finish by 3 p.m. and I'll call you back then.
After a disappointing year, figures for the first half of 2004 have been encouraging and we should / ought to / expect to
achieve our target profit figures by the end of the year.
2. Expressing probability
Ought to and should can be used to express probability.
For example:
You should / ought to receive the goods on Tuesday.
The Chairman should / ought to have arrived at our Toronto office by now.
The suggestion here is :
You probably will receive the goods on Tuesday.
He probably is in the Toronto office, but I'm not certain.
Again, the two verbs are more or less interchangeable, although ought to is slightly stronger.
3. Expressing desirability
Another use of both ought to and should is to express desirability:
You should / ought to have stayed for the last day of the conference, it was very interesting.
4. Expressing an obligation or duty, giving advice
Lastly, ought to and should can also be used to express a duty, or to give advice.
For example:
You should / ought to look at our prices, they are very competitive (I'm suggesting, giving you some advice).
You should / ought to study the figures before the meeting (you are strongly advised to ?).
You should / ought to rewrite your presentation (indicating an obligation).
Obviously, must could also be used in this context, to express an even greater degree of obligation:
You must study the figures before the meeting.
You must rewrite your presentation (you have no choice in the matter).
Nowadays, should is used much more frequently than ought to. This is a shame, particularly as many grammarians consider
that there is a difference between the two: Webster's, for example, states that "both words imply obligation, but ought is
the stronger. Should may imply merely an obligation of propriety [proper or correct conduct]; ought denotes an obligation
of duty."
5. Negative / interrogative form
The negative and interrogative forms of "ought to" are used only very rarely:
Such things ought not happen.
You ought not to have said that.
What things ought you to know?
It would be much more usual to say such things should not happenor you shouldn't have said that.
Finally, an interesting example of usage of the verb ought in the negative form hit the headlines in September 2001: when
the FBI was asked to comment on a leaked secret memo its spokesperson said " There are lots of things the intelligence
community knows and other people ought not to know."
