Should an infinitive be treated as a subject or object? For example, in 'I want to know it', is the 'to know' subjective or objective?

  • The to-infinitive, lacking tense and number, refers to the bare idea of the verb's action. To walk. To swim. To eat. It is almost an abstract noun, conceptually.The -ing form can be substituted for it when it occupies the subject position in a statement: Walking is good for you. Swimming is fun. Eating is necessary for life. Mar 28, 2016 at 8:57
  • To walk is good. To swim is fun. To eat is necessary. Though we often use the dummy "it" in such statements. It is good to walk. It is fun to swim. It is necessary to eat. Mar 28, 2016 at 9:03
  • What about "I like to eat fruit"?
    – JavaLatte
    Mar 28, 2016 at 9:30
  • Adding a direct object to the to-infinitive refers to the bare idea of the infinitive verb phrase. {Eating fruit} is good for you. I like eating fruit. Mar 28, 2016 at 9:51
  • If all that is being asked is what is the grammatical role of "to know it" in the sentence "I want to know it", then the infinitive-phrase occupies the object argument slot, "I" occupies the subject argument slot, of transitive verb "want". Mar 28, 2016 at 10:00

1 Answer 1


Let me give you two views on this. Part one is my preference.


Generally, infinitive can act like an adverb, adjective, and a noun in a sentence. As a noun (or a noun substitute), an infinitive can function as the complement, subject or the object of the sentence.

As the subject:

To go, even after all that trouble, didn’t seem worthwhile anymore.

To err is human.

As the complement:

My goal is to write.

And finally the object for which you gave an example:

He wants to see.

Here to see is the object. To see is generally what he desires.

In your example to know it is what I desire and then is the object of want.


"to know it" in your example is a complement. According to Cliff, complements are Noun Clauses (i.e, clauses used as nouns), and they may function either as Subject or as Direct Object. Complements are of different kinds one of which is infinitive clauses. The other two are gerund and that clases.

Based on Cliff's classification. "To know it" is a non-finite infinitive clause which is the object of the sentence.

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However, in either case, it's the object in your example.


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