"To infinitives" are often used as adjectives and adverbs to indicate purpose.

I have something to eat.

He came to play.

When we use "to infinitives" with adjectives like anxious and unwilling, are they said to indicate purpose, or do they indicate something else?

He was anxious to play.

He was unwilling to play.

This building is built to last.

Wikipedia's description says that "to infinitives" modify adjectives, but it doesn't say how it modifies the adjective. There seems to be a difference between a sentence like "he was unwilling to play" and "it is tall to reach fruit" in how the infinitives modifies, but if we say the infinitive in the first sentence does not indicate purpose, then I'm not sure what we would say it indicates. For example, when a "to infinitive" indicates purpose, it can be reworded to "in order to" or "for the purpose of" but I'm not sure how I would reword sentences like "he was anxious to play" or "he was unwilling to play."

2 Answers 2


The infinitival clauses in your examples are all, with one exception, complements, not modifiers (adjuncts).

I have something to eat.

"To eat" is an infinitival relative clause in which "something" is object of "eat" (cf. I have something that I can eat.) The clause is modifying "something".

He came to play

The infinitival "to play" is catenative complement of "came".

He was anxious to play.

He was unwilling to play.

This building is built to last

In those three examples, the infinitival clauses are not modifiers, but complements to the adjectives concerned.

  • So the to-infinitives in the last three sentences don't indicate purpose in the way the to-infinitive in "I have something to eat" does?
    – Joe
    Commented Jan 26, 2016 at 22:52
  • @Joe No, they just add meaning to the adjectives by explaining what it is that he was "anxious", "unwilling" about, and what it is that the building is "built" to do. Elements that indicate purpose are called adjuncts (or adverbials); they modify verbs and VPs, not adjectives, for example "I checked the doors [to make sure they were locked]". There the bracketed infinitival clause is modifying the verb phrase "checked the doors"; it explains the purpose of doing that.
    – BillJ
    Commented Jan 27, 2016 at 9:51
  • +1 Are you sure about to play being a catenative complement there though? Isn't that an Adjunct meaning in order to play? I'd understand o pass as a catenative complement in It came to pass but is doesn't seem like one to me in the original example. Commented Jan 28, 2016 at 15:22

In these sentences the "to infinitives" function as noun objects for transitive verbs. Both anxious and unwilling express desire (or the lack there of). One may desire many things, including objects that are obviously nouns or events that may appear to be hard to categorize because they are described using verbs. For grammar purposes, these events just function as complex noun phrases. If the event is an action performed by something other than the subject, then we are forced to state the actor. If it is an action performed by the subject, however, we normally refrain from repeating this fact. Consider the following examples:

He wants a cookie. He wants to play. He wants the dog to play.

Your example of something to eat does not convey purpose. In that sentence "to eat" is an adjective describing the noun "something."

  • 1
    I have edited your answer and the OP's question to put quotation marks around every instance of "to infinitive". It does make comprehension far easier if you observe basic punctuation requirements of this kind.
    – WS2
    Commented Jan 26, 2016 at 9:34
  • @WS2 The orthographic convention is usually: to-infinitive / to-infinitive though. I don't think I've ever seen ' "to infinitive" ' before. Commented Jan 26, 2016 at 10:25
  • 2
    @Araucaria There is always a first-time! Bear in mind I am not a professional in this field. But with no punctuation of to infinitive at all, the text can be baffling.
    – WS2
    Commented Jan 26, 2016 at 12:50

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