Infinitive Clauses

In English grammar, an infinitive clause is a subordinate clause whose verb is in the infinitive form. Also known as an infinitival clause or a to-infinitive clause

The infinitive clause is called a clause because it may contain such clausal elements as a subject, object, complement, or modifier. Unlike most other subordinate clauses in English, infinitive clauses are not introduced by a subordinating conjunction.

Verbs that can be followed by infinitive clauses (as objects) include: agree, begin, decide, hope, intend, like, plan, and propose.

Examples and Observations

• "I'm sorry but there's a handsome man in my spoon. You'll have to come back later."
  (Tom Tucker, "The Kiss Seen Round the World." Family Guy, 2001)
• Jane was firm in her desire to live life on her own terms.
• Desperate to prove his innocence, Jamal tells the story of his life in the slums of Mumbai.
• "If you want to make God laugh, tell him about your plans."
  (Yiddish proverb)
• "We merely want​ to live in peace with all the world, to trade with them, to commune with them, to learn from their culture as they may learn from ours, so that the products of our toil may be used for our schools and our roads and our churches and not for guns and planes and tanks and ships of war."
  (President Dwight Eisenhower, quoted in Time magazine, 1955)

Infinitive Clauses as Subjects and Objects

"A subordinate clause with an infinitive often acts as the subject or object of the main clause. In the following examples, the whole infinitive clause [in bold] is understood as the subject of is human, is decadent or was unnecessary.

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Definition and Examples of Infinitive Verbs

By Richard Nordquist

- To err is human.
- To drink Martinis before noon is decadent.
- For Mervyn to redirect Maggie's mail was unnecessary.

And in the following examples, the whole infinitive clause [again in bold] is understood as the direct object of hates, loves and expected.

- Jim hates to wash his car.
- Rosie loves to plan parties.
- Phil expected Martha to stay at home all day.

In case this is not obvious at first, you can test this by answering questions such as What does Jim hate? (answer: to wash his car), or What did Phil expect? (answer: Martha to stay at home all day)." (James R. Hurford, Grammar: A Student's Guide. Cambridge University Press, 1994)

Perfect Infinitives

"To express time preceding that of the main verb, the infinitive takes a perfect form: 'to' + have + past participle.

(58) The parents were lucky to have found this specialist for their sick child.

The perfect infinitive can be used with progressive aspect to emphasize duration. This construction consists of 'to' + have + been + V-ing.

(59) He was too scared of the police to have been telling lies all the time.

(Andrea DeCapua, Grammar for Teachers: A Guide to American English for Native and Non-Native Speakers. Springer, 2008)

Passive Infinitives

"An infinitive that is derived from a passive finite verb clause will itself be passive:

(20) a. I expect that all the calamari will be eaten before 7:00. (passive verb)
(20) b. I expect all the calamari to be eaten before 7:00. (passive infinitive)

You can verify that to be eaten is a passive infinitive in (20b) because it contains the passive marker [BE + (-en)]: be eaten. Remember that eaten is a transitive verb; in its active form, it will have a subject (an indefinite pronoun like someone or they) and a direct object (all the calamari)." (Thomas Klammer et al., Analyzing English Grammar, 5th ed. Pearson, 2007)