Uses of the to-infinitive

Look at the following sentences:

  • To err is human.
  • To retreat now would be a disgrace.

What are the subjects of these two sentences? You will have noticed that they are ‘to err’ and ‘to retreat’ – both infinitives. Thus we have seen that the to-infinitive can be used as a noun to form the subject of a sentence.


Although the to-infinitive can be used as the subject of a sentence, it is more common to write these sentences with a preparatory it as the provisional subject.

  • It is human to err.
  • It would be a disgrace to retreat now.

To-infinitive as the object

Study the following sentences.

  • John likes to swim in the sea.
  • Alice decided to meet the principal.
  • Peter wants to go abroad.

John likesĀ  … what? To swim in the sea
Alice decided … what? To meet the principal
Peter wants … what? To go abroad

Here the infinitives to swim, to meet and to go are the objects of the verbs likes, decided and wants respectively. The to-infinitives are thus used as nouns to form the objects of transitive verbs.

To-infinitives as subject complements

Read the following sentences.

  • The best thing to do now is to vanish.
  • Your duty is to support her.

Here the to-infinitives to do and to support are the complements of the subjects thing and duty.