Infinitives
The Blue Book of Grammar and Punctuation
Infinitives
Every English verb has an infinitive, which is the base form of the verb before it is conjugated. It consists of the word to and the present form of the verb (the infinitive stem): e.g., to run, to sing, to write, to follow.
Although an infinitive is the base of a verb, it does not function as one. Rather, it will serve a sentence as a noun (subject, subject complement, or direct object), an adjective, or an adverb. When operating in these ways, if the infinitive has any modifiers, the entire infinitive phrase is included in the part of speech.
Examples
To sprint faster is the challenge Nathan set for himself.
She gave him the envelope to bring to his boss.
Billy wants to play soldiers, but Robby would like to play marbles.
Infinitives as Subject Nouns
An infinitive or an infinitive phrase can function as the thing or idea the sentence is about, making it a noun.
To make a mistake in this business is common.
To wait seems futile right now.
To swim in the roped-off area of the beach might not be a good idea.
To ace the exam will be Ryan’s next primary goal.
Note that the subject in the second example is an infinitive, and the other three sentence subjects are infinitive phrases.
Infinitives as Subject-Complement Nouns
Infinitives and infinitive phrases can identify or describe a sentence subject as its noun complement.
Ryan’s next primary goal will be to ace the exam.
Your best option could be to run for board treasurer.
The mayor’s final decision was to keep the bridge open.
Hamlet’s goal is to be.
The first three examples have infinitive phrases as subject complements, and the subject complement in the last example is an infinitive.
Infinitives as Direct-Object Nouns
Infinitives and infinitive phrases can receive the action of the verb in a sentence. This can include an infinitive that is part of a direct object preceding it.
I would like to learn more about the space program before I join it.
Joel asked Stephanie to meet him by the shoe store.
The rattle made the baby (to) smile.
Everyone plans to go.
The first two examples include infinitive phrases as direct objects. In the last example, the direct object is an infinitive.
In the third example, the baby is the subject of the infinitive to smile, and the infinitive phrase the baby to smile is the direct object of the verb made. The word to is placed in parentheses to indicate it is typically omitted as understood in standard writing and speech. You may see such omission with certain other infinitives as well:
Arnie kept the frogs in a bucket for a week and then decided to let them (to) go.
He dared not (to) speak after learning they’d found out about his secret trip to Alaska.
Infinitives as Adjectives
Infinitives and infinitive phrases can modify nouns as adjectives in sentences. This can include an infinitive that appears after another adjective within an expletive construction such as it is.
Please give Annette this clipboard to write on.
It is wonderful to have a hobby you enjoy.
I must go now because I have a job to do.
Carmen and Carlisle had something common to discuss.
The first example has an infinitive with a particle (write on) describing a noun (clipboard). In the second, an infinitive phrase further modifies the adjective wonderful. The third example is an infinitive describing job, and the fourth, like the second example, further modifies an adjective (common).
Infinitives as Adverbs
Infinitives and infinitive phrases can act as adverbs modifying verbs, adjectives, or other adverbs.
Johnny joined the military to serve his country. (adverbial infinitive phrase modifying main verb joined)
Amy went to the mall to shop. (adverbial infinitive modifying main verb went)
The space explorers were amazed to discover a boiling lake on the distant planet. (adverbial infinitive phrase modifying adjective amazed)
Would you show me affection merely to gain my fortune? (adverbial infinitive phrase modifying adverb merely)
Related Topic
Split Infinitives: To Split or Not to Split
Pop Quiz
Applying what you now know, identify the infinitive or infinitive phrase and its function (noun, adjective, adverb) in each sentence.
1. To show his devotion, Peter waited an hour in the rain for Bonnie’s arrival.
2. The Wilsons have always found it splendid to plant flowers in the spring.
3. To work until fatigue sets in is always a possibility at this job.
4. Amber’s ambition is to achieve a lasting peace in her neighborhood.
5. Amber wants to achieve a lasting peace in her neighborhood.
Pop Quiz Answers
1. To show his devotion, Peter waited an hour in the rain for Bonnie’s arrival. (adverb)
2. The Wilsons have always found it splendid to plant flowers in the spring. (adjective)
3. To work until fatigue sets in is always a possibility at this job. (noun—subject)
4. Amber’s ambition is to achieve a lasting peace in her neighborhood. (noun—subject complement)
5. Amber wants to achieve a lasting peace in her neighborhood. (noun—direct object)
If the article or the existing discussions do not address a thought or question you have on the subject, please use the "Comment" box at the bottom of this page.
For pop quiz #2, I am having a hard time understanding how “to plant flowers in the spring” fits the mold of an adjective. It does not modify “The Wilsons” and it does not seem to modify “splendid” The infinitive phrase appears to be a delayed appositive of “it.” The Wilsons have always found it(planting flowers in the spring) splendid. Am I missing something? If so, can you clarify this sentence.
The quiz question (#2) you are inquiring about is similar to what is discussed in the article section “Infinitives as Adjectives.” In that section, one example is It is wonderful to have a hobby you enjoy. In this construction, the infinitive phrase is an extension of the adjective “wonderful.”
We can look at the text in question as a similar separate construction: It is splendid to plant flowers in the spring. In the quiz question, the syntax of the sentence is adjusted to make the construction support an object role.
If the infinitive phrase in “It is wonderful to have a hobby you enjoy” modifies the adjective “wonderful,” and if the infinitive phrase in “Carmen and Carlisle had something common to discuss” modifies the adjective “common,” why are the infinitive phrases not considered adverbial? That is, infinitives acting as adverbs?
Thank you.
Technically, adverbs can modify both adjectives and other adverbs. Plus, an infinitive is a verb phrase, which is genetically closer to an adverb than to an adjective.
With infinitives, however, there are subtleties at work. In other words, an adjectival infinitive phrase might not be as easily recognizable as a standard adjective often is. In the examples, the infinitive phrases do not serve an adverb’s function to communicate place, time, manner, circumstance, degree, or cause. In other words, they do not address when, where, how, or why:
It is wonderful to have a hobby you enjoy.
Carmen and Carlisle had something common to discuss.
In comparison, let’s look at infinitive phrases serving as true adverbs:
He ran quickly to arrive on time. (The infinitive phrase addresses the cause of running quickly.)
Would you show me affection merely to gain my fortune? (The infinitive phrase elaborates on the “why” behind “merely.”)
Your book defines an adjective as a word or set of words that modifies (i.e., describes) a noun or pronoun. Adjectives may come before the word they modify.
So, in the second example, an infinitive phrase further modifies the adjective wonderful. The third example is an infinitive describing job, and the fourth, like the second example, further modifies an adjective (common).
Can adjectives modify adjectives?
Adjectives modify nouns and pronouns. As the post says, “Infinitives and infinitive phrases can modify nouns as adjectives in sentences. This can include an infinitive that appears after another adjective within an expletive construction such as it is.”
The infinitive phrase “to gain my fortune” adverbially modifies the verb “would show” in “Would you show me affection merely to gain my fortune?” It qualifies the reason or purpose for showing affection (why show affection? to gain fortune). The infinitive does not modify the adverb “merely”; instead, “merely,” which is equivalent to “only,” modifies the infinitive.
It is understandable to interpret the modifying infinitive phrase in the way you identify. The subtle adjustment in function can be better seen if we remove the infinitive phrase: “Would you show me affection merely?” This changes the meaning of the sentence. In the context presented, “to gain my fortune” adds to the meaning of “merely.”
Yet another way to view the function of the grammatical parts is to move the infinitive phrase in the sentence: “To gain my fortune, would you show me affection merely?” Once again we see an altered meaning. In the original sentence, there is a dependency between “merely” and “to gain my fortune” in conveying the intended idea.
For the example “It is wonderful to have a hobby you enjoy,” it is not true that the “infinitive phrase further modifies the adjective ‘wonderful.'” The word “it” is used in its expletive role and anticipates the true subject, the infinitive phrase “to have a hobby you enjoy,” which consequently functions as a noun. Consider: “To have a hobby you enjoy is wonderful.” An infinitive phrase following an adjective is not just another adjective. Adjectival infinitive phrases modify nouns.
We are both correct. In the example cited, the infinitive phrase can serve (and grammatically qualify) both as the true subject delayed by the expletive, making the phrase a noun, and as an adjective further modifying the primary adjective. Expletive constructions are uncommon in this way.