Linguistic Overview
“To be, or not to be, that is the question.” — Hamlet
Full Infinitives are never used as standalone verbs, though they can be the main verb of a sentence following certain modals and future tense indicators. As verbals, Full Infinitives can be complements following the main verb (as in “need to breathe” or “try to remember“), an adjective (as in “able to rise” or “funny to think about”) or a noun (as in “failure to launch” or “a sight to behold“). These infinitives often convey purpose or intent, though they can instead refer to an unintended result.
Full Infinitives are often prospective, meaning they are future-facing. When paired with another verb, the infinitive would potentially take place after the main verb (see the Verb Patterns section below). Some of the common future forms in English make use of Full Infinitives: most notably the be going to form is in part a Full Infinitive.
Full Infinitives are distinct from Bare Infinitives, which do not have the to particle (eg: ‘to go’ is a Full Infinitive, while ‘go’ is a Bare Infinitive). Bare Infinitives aren’t prospective and don’t carry a meaning of purpose like Full Infinitives do.
Form
Full Infinitives
The Full Infinitive is simply a verb’s base form (as you would find it in the dictionary) fronted by the particle to. A particle is a small word that carries no meaning on its own but instead is purely functional. There should be no other morphological change to the verb (like ending in an -s, -ed, or -ing), regardless of how its used.
For example, the Full Infinitive forms of smile, dry, and wonder are simply ‘to smile’, ‘to dry’, and ‘to wonder’, respectively.
Full Infinitive Phrases
Sometimes a Full Infinitive may come at the head of a phrase. Within the scope of the phrase, the infinitive retains the properties of a verb: it may be modified (perhaps by an adverb or a prepositional phrase) or have complements (like direct objects). Here are some example Full Infinitive phrases:
- “to smile maliciously” ← a Full Infinitive modified with an adverb
- “to dress in style” ← a Full Infinitive modified with a prepositional phrase
- “to dry your eyes” ← a Full Infinitive complemented by a direct object
- “to be a dentist” ← a Full Infinitive complemented by a predicative nominal
- “to feel exhausted” ← a Full Infinitive complemented by a predicative adjective
While the Full Infinitive itself acts much like a verb, the phrase as a whole can serve as a noun or modifier, as shown below.
Verb & Verb Complement Applications
The different applications that follow are not necessarily distinct from one another, and there are plenty of instances that might be classified as more than one of the following.
Verb Patterns
Verb Patterns are the combination of the main verb of a clause with a following verbal (either an infinitive or a participle). The second parts of most Verb Patterns are either the to- form (Full Infinitives) or the -ing form. Some examples of infinitive Verb Patterns are:
- “would love to hang out“
- “stop to smell the roses”
- “forbid [someone] to trespass“
- “forgot to walk the dog”
- “seems not to notice“
- “prepared to take action”
In many cases (though not quite all of them), the Full Infinitive remains prospective — that is, the infinitive would occur after the main verb. For instance, ‘take action’ comes after ‘prepare’, and ‘smell the roses’ comes after ‘stop’, from the examples above. Additionally, in many cases the infinitive communicates purpose, or perhaps a result.
Future Forms
As mentioned before, Full Infinitives tend to be prospective. This means they would typically occur at least after the main verb. But they might also be used as the main verb to firmly place the action or state in the future. (See Future Plans and Future Predictions.) One of the most common future forms — be going to — employs infinitives to do just that, and it’s not the only way to express a future verb:
- “We are going to visit my grandparents this summer.”
- “He is about to sneeze!”
- “I am planning to apply to colleges soon.”
- “It is expected to rain today.”
The same goes for Future-in-the-Past, as in “I was going to tell you the truth, but then we got interrupted.”
Modality
Ought and Pseudo-Modals
While the core modal verbs should be followed by the Base Infinitive (meaning there is no to particle), the marginal modal ought and the pseudo-modals care, dare, get, have, have got, need, tend, and used should instead be followed by the Full Infinitive. For example:
- “You ought to know better!”
- “I have got to quit smoking.”
- “Susie used to climb trees when she was young.”
- He didn’t dare to disobey again.”
Notice that this format overlaps with Verb Patterns.
Modal Suppletives
Sometimes a modal verb should be replaced by a phrase that is more grammatically flexible. These are called periphrastic substitutes, and the verbs that follow them should be in the Full Infinitive form.
- “Charlie was able to pull his friend out of the pit.” (instead of could)
- “You‘re supposed to rest if you’re feeling sick.” (instead of should)
- “No one is allowed to go backstage.” (instead of can)
See the ‘Modifying Adjectives’ subsection below for similar applications.
Modifier Applications
Adverbials of Purpose or Result
Modifying Verbs
Full Infinitives are great for answering “Why?”:
Why did the bear go over the mountain? To see what he could see, that’s why!
The reason that the bear ventured over the mountain was for the purpose of sightseeing or exploration. Similarly, in “Jack and Jill went up the hill to fetch a pail of water,” we are told what Jack and Jill’s intention was. This idea is even more pronounced when Springsteen says he was “born to run,” as if it’s the purpose of his very life.
In these examples, “to see what he could see” and “to fetch a pail of water” could either be seen as infinitive phrases or as Adverbial Clauses. In either case, these phrases/clauses modify the main verb of the sentence and thus are adverbials.
We could also add the phrase ‘in order’ before the infinitive — as in “Jack and Jill went up the hill in order to fetch a pail of water,” — without changing the meaning.
Modifying Adjectives
The Full Infinitive can modify adjectives when those adjectives follow be or get. These infinitives communicate intention.
- “Get ready to rock!”
- “She’s not able to speak yet.”
- “What’s the best way to travel?”
They can also modify superlative adjectives, especially ones that are followed by a noun. These infinitives usually communicate result.
- “The last one to finish is a rotten egg!”
- “Maximus was the greatest champion ever to enter the arena.”
With ‘Too’ or ‘Enough’
The adverbs too and enough are often followed by Full Infinitives as in:
- “This box is too heavy to lift.”
- “There is not enough water to fill the tub.”
- “Have you had enough to eat?”
Too and enough are often relative terms that generally depend on context, sometimes specifically on purpose. For example, “Is this dress too fancy?” It might be too fancy for a relaxing afternoon, but not too fancy for an anniversary date. Perhaps it’s not even fancy enough for a grand ceremony. In other words, it depends on the purpose for which you are wearing the dress.
after Imprecise Nouns or Pronouns
Full Infinitives can act like restrictive modifiers for imprecise pronouns or other pro-forms, or for generic nouns (that are not otherwise specified by the context), helping to narrow their meaning and provide clarity (similar to how Relative Clauses might work). This tends to apply to ‘WH’ Words, Quantifier Pronouns, and Indefinite Pronouns.
- ‘WH’ Words
- “I don’t know whom to trust.”
- “Show me where to go.”
- Quantifier Pronouns
- “We still have much to learn.”
- “They brought plenty to share!”
- Indefinite Pronouns
- “Could I have something to eat, please?”
- “You’ve got nowhere to run!”
- Generic Nouns
- “Of all these competitors, Jenson is the man to beat if you want first place.”
- “If you’re looking for answers, Barbara is the person to ask around here.”
In each of these instance, the infinitive reveals the speaker’s or subject’s intent.
Nominal Applications
Although it’s not terribly common, especially in casual speech, Full Infinitive phrases can be used as nouns. As such, they may fill the role of subjects, objects, predicate nominals, etc. Examples include “To err is human,” and “What I really need is to go on vacation.” This usage of Full Infinitive phrases is very similar to Gerund phrases.
Teaching Tips
Meaning Tied to Verb Forms
By the time you cover Full Infinitives with your students, there’s a good chance they’re already familiar with Active Participles and Perfect Participles. In that case, you can show how infinitives and and participles are similar. Both can be verbals, meaning they can serve as the head of modifier phrases or noun phrases instead of as verbs.
Each type of participle and infinitive is known by its form, but importantly each also carries a meaning with it. Just as the -ing form conveys an action in progress and the -ed/en form communicates some aftereffect of the verb, the to- form relates a prospective meaning and intent.
Impress upon students that these general meanings are tied to their corresponding verb forms; you can rarely have the form without the meaning.
Split Infinitives
A false grammar rule is to never split an infinitive, which means there should be no words between the to particle and the base verb form. For example, “To boldly go where no man has gone before,” is ostensibly wrong, and we should instead say “To go boldly where no man has gone before.” But that second sentence doesn’t sound as good. The real issue, though, is that the original rule was for Latin, which formed verb forms different than English does. In Latin, would could not literally split an infinitive without just making up some new words on the spot. English is flexible enough that this is not a problem.
Bottom line: ignore this fake rule. It is perfectly okay to split an infinitive with an adverb.
Further Reading
| Related Concepts | Applied Grammar Topics |
|---|---|
Infinitives & Participles
Types
Bare Infinitives • Full Infinitives • Active Participles • Perfect/Passive Participles
Full Infinitive topics
Active Participle topics
Active Adjectives • Future Continuous • Gerunds • Participial Phrases • Past Continuous • Present Continuous • Present Perfect Continuous • Verb Patterns
Perfect Participle topics
Future Perfect • Perfect Modals • Participial Phrases • Past Perfect • Present Perfect • Present Perfect Continuous
