Semi-modal verbs – ought to

For many of your, reading this post will be one of the few times (if not the first time) you have seen “ought to”, the next semi-modal verb on our list. But what is it and why are we including it on our list? What does it even mean?

It is a semi-modal verb that has two meanings:

  1. to indicate the correctness of something or to indicate a duty (usually used when criticising someone’s actions)
  2. used to show that something is probable

As you can see, “ought to” is two words, which makes it a semi-modal verb rather than a modal verb. However it shares all of the other characteristics of modal verbs, meaning that it comes first in a series of verbs, it cannot be combined with another modal verb and does not change form depending on the person. For example:

During this pandemic we ought to exercise more.

This shows something that is correct or indicates a duty to do something.

Thirty minutes ought to be enough to finish this quiz.

This shows that something is likely or probable.

The word “ought” is a very old word in English, coming directly from Old English (with a few changes) and related to the verb “to owe”. Until the past few hundred years, you could say “He aught me five pounds” as the past tense of “owe”. Now it is “owed” and the meaning has become more of owing a duty to someone or something rather than owing something physical.

Ought can also be used in the negative sense. Like other semi-modal verbs, the word “not” comes after the word “ought”. For example:

You ought not to have done that.

The full form

You can also shorten “ought not to” to “oughtn’t to”:

You oughtn’t to have done that.

The contracted form

Although “oughtn’t to” exists, today English speakers usually use “shouldn’t” instead of “oughtn’t to”. For more differences between “ought to” and “should”, you can find the differences under should vs ought to vs had better.


Want to learn more about modal verbs? Here is a guide to all the semi-modal verbs: introduction to semi-modal verbs. You can also learn more about other English language information on my Teaching English page.

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