I’m going to explain nonfinite verbs because I’ve been unable to find a good conceptual explanation for them that I could refer people to. They’re very common in English and they come up frequently when analyzing text in detail (as philosophers sometimes do).
This is an intermediate level article. You should already be familiar with gerunds, participles and infinitives, and have done some grammar practice involving them. Otherwise start with English Language, Analysis & Grammar and my Text Analysis video playlist.
My main goal here is to explain some concepts that will help people who already have a learning process underway. I skip some steps like giving examples of typical non-finite verbs.
A complete, independent thought in English requires a verb, subject and tense. The verb is the action of the sentence. The subject is the actor. The tense tells us about the timing of the action. There’s often an object, which is the thing acted on. And there are often modifiers which provide additional details.
Conjunctions allow us to put multiple thoughts in one sentence. Without something to combine thoughts together, we express one complete thought per sentence.
Besides action verbs, there are linking verbs. They link two things together. For example, in “The ball is red.” the linking verb “is” links “ball” with “red”. Linking verbs can be thought of like a “being” action. For the rest of this article, I’ll talk about verbs as involving action, without differentiating links. (English has lots of special cases. The rules aren’t 100% consistent. Anything in this article may have exceptions.)
When a verb is used for a complete thought, it’s called a “finite” verb because its possibilities are limited to that specific thought. It’s a regular, normal verb.
We can also use verbs for incomplete thoughts. These are called “nonfinite” verbs. In terms of the roles words have in a sentence, nonfinite verbs function as a noun or modifier. Although they have some characteristics of verbs, they don’t perform the verb role and can’t be used to replace a (finite) verb.
Nonfinite verbs let us reuse the concepts from verbs for other speech. They let us get more use of the words we have instead of having to invent more words.
Verbs are the starting points of sentences and thoughts. They play a leading, governing role. So let’s look at a verb by itself.
“throw” isn’t a complete thought. (Unless it’s a command that’s telling you to throw in the present, so there’s an implied subject.)
We can make “throw” more specific and complete by adding details.
“throw the ball” tells us what should be thrown.
“throw over there” tells us where to throw.
“throw quickly” tells us in what manner to throw.
“throw well” tells us the quality of the throwing.
“threw” tells us the throwing happened in the past.
These examples are incomplete thoughts.
“John throw” tells us who does the throwing, but it’s still incomplete. The base form of the verb, “throw”, hasn’t been conjugated to tell us the tense and agree with the subject. (Besides being the base form, “throw” is also the present tense that agrees with the first and second person subjects “I” and “you”. English often uses the same word for multiple purposes which can be confusing.)
“John threw great pitches in the baseball game.” is a complete thought. It’s a valid sentence. It tells us that throwing happened in the past and was performed by John. It also provides additional, optional detail about what was thrown (pitches) and the context (the baseball game).
“John throws.” and “John threw.” are valid, complete sentences too, but they’re somewhat confusing with no context because we don’t know what was thrown, why or how. They don’t leave out mandatory grammatical information, but they’re poor communication in isolation. They do provide the information of an action, time and actor, which are required by English for completeness. (We don’t usually specify exact times, but some information about time is required. At minimum, a complete thought specifies present or past.)
You can think of the process of building a (simple) sentence as starting with a verb. Then you add details until your thought is complete. But a nonfinite verb is inherently incomplete, so you can’t form a sentence around it.
Complete things are finite. Nothing is left unbounded or unspecified. Incomplete things have details left blank which could be completed in an unlimited number of ways. They’re infinitely variable based on all the possibilities for how they could be completed.
Complete things are also independent. They stand alone, by themselves. If something doesn’t work by itself, then it’s incomplete in some way. When a verb is used for a noun or modifier meaning, it doesn’t form a complete, independent thought, just as nouns or modifiers depend on other words.
Actions and Concepts
The word “running” is a nonfinite verb based on the verb “run”. It’s often a noun which refers to the concept of running rather than saying that a running action happened at some time. The concept of running can be considered in the abstract with no runner. “Running” can also be a modifier, e.g. in “I saw running water.”.
When a thought is incomplete, that makes it ambiguous. There are multiple possibilities for what it could mean. For example, when a verb has no subject, then anyone or anything could be the subject. There are infinitely many possibilities. That’s why the incomplete verbs are called “nonfinite”.
Finite verbs tell us that some action actually happened or is happening (though we can use finite verbs to speak hypothetically, fictionally or abstractly). And they tell us the subject: who or what acted or is acting. The core ideas of a finite verb are an action at a time by an actor.
Nonfinite verbs are used to refer to actions without them actually happening. In “I want to leave.”, the nonfinite verb “to leave” talks about an action without anyone doing it. The action here is wanting. Leaving is a concept.
In “I want him to leave.”, leaving is still a concept. The sentence expresses that I want something, and what I want is the concept of him leaving. By contrast, “I requested that he leave.” uses “leave” as a finite verb (“requested” is also a finite verb). I requested an action not a concept.
In “I saw running water.”, “running” tells us a trait of the water rather than telling us an action. In “I like running.”, “running” is a concept not an action. “Running is fun.” uses running as a thing (a concept), and the action of the sentence is the link between running and the trait “fun”. “I ran yesterday.” tells us an action while “I was running yesterday.” uses “running” as a trait and the action of the sentence is to link “I” to a trait.
Nonfinite verbs use a word that’s based on a verb to communicate an idea, concept, trait or thing instead of communicating a complete thought about an action that happened or is happening.
Nonfinite verbs usually don’t have a subject, but they sometimes do. They can be incomplete in other ways too, for example by having no tense. Tense tells you when a verb’s action happened, like in the past or present. They’re also incomplete by functioning as a noun or modifier, not a complete, independent idea.
In English, there are three types of nonfinite verbs. Gerunds and infinitives never have tense. Participles do have past and present tense, though it may not be identical to the way finite verbs have tense.
Gerunds are nouns which end in “ing”. Participles are modifiers which normally end in “ing” (present tense) or “ed” (past tense). Infinitives are nouns or modifiers. Infinitives sometimes have “to” in front, and always use the base form of the verb which sounds correct with “to” in front (e.g. “to clean” or “to paint”). Infinitives don’t use the verb forms ending with “s” or “ed” (like “cleans” or “cleaned”).
Tips: Words ending with “ing” are always nonfinite verbs. Words with “to” in front aren’t finite verbs.
In what ways can a nonfinite verb be incomplete? Common missing things include tense, subject, object, mood and case.
New Oxford Dictionary explains verb mood:
Grammar a category or form which indicates whether a verb expresses fact (indicative mood), command (imperative mood), question (interrogative mood), wish (optative mood), or conditionality (subjunctive mood)
English has three main cases which are primarily used with pronouns. For example, “I” is the case indicating a subject, “me” indicates an object, and “my” indicates possessive. I/me/my are different forms of the same word which indicate different cases. When we aren’t using pronouns, the subject and object case are the same, e.g. “John” or “ball” can be a subject or object. The possessive case (“John’s” or “ball’s”) is different though.
Finite verbs use subject case for their subject and object case for their object. E.g. “He saw him.” shows different cases of the same word for the subject (“he”) and object (“him”).
Nonfinite verbs don’t specify case. They use object case for both subjects and objects. For example, consider “I regretted him leaving the company.” or “Him leaving the company was really hard for us.”. In both examples, the subject of the gerund “leaving” is “him” not “he”, even though “he” is the subject form of the word. Similarly, in “I wanted him to sing”, the subject of the infinitive “to sing” is “him” not “he”. Note, in the first example, “leaving” is the object of “regretted”. In the second example, “leaving” is the subject of “was” and “to sing” is the object of “wanted”. “Leaving” and “to sing” both play a noun role. The finite verbs are “regretted” and “was”.
If you want to read more about nonfinite verbs, Wikipedia is actually one of the best online sources of detailed grammar information. Links: nonfinite verbs, participles, gerunds, infinitives, the -ing suffix, using nonfinite verbs.
Finite verbs lead clauses. They, along with the rest of their clause, provide some reasonably specific information. Because they’re specific, there are limited (“finite”) possibilities for the meaning.
Non-finite verbs don’t lead clauses. They’re instead involved in a grammatical construction (group of words) that is smaller than a clause and is nested within a clause. Because their group doesn’t have all the information of a clause, something is left out, missing, unspecified. In some sense, the unspecified part could be anything. In other words, in some sense, there are unlimited (infinite) possibilities for how to fill in the blank.
A finite verb and its clause don’t have a blank spot like that, thus limiting the possibilities. A non-finite verb always does – it’s word grouping is always incomplete in some way compared to a clause.