8.3 Functions of non-finite clauses

Non-Finite Clause Functions

Non-finite clauses can fill almost any role in a sentence that a noun, adjective, or adverb can. They let you pack more information into a sentence without needing a full finite clause (one with a subject and tensed verb). The key is knowing which role a non-finite clause is playing, because that determines how it connects to the rest of the sentence.

Functions of non-finite clauses

Non-finite clauses serve six main functions. Here's a quick overview before we look at each one in detail.

• Subject — The non-finite clause acts as the subject of the sentence.
  • Reading books broadens your mind. (gerund clause as subject)
  • To succeed requires dedication. (infinitive clause as subject)
• Object — The non-finite clause follows a transitive verb and receives the action.
  • She enjoys swimming in the lake. (direct object)
  • They asked me to help with the project. (object of "asked")
• Complement — The non-finite clause completes the meaning of a subject or object.
  • Subject complement: Her goal is to become a doctor.
  • Object complement: We found the movie to be entertaining.
• Adverbial — The non-finite clause modifies the verb, expressing time, reason, purpose, or condition.
  • After finishing work, she went home. (time)
  • She left early to catch the train. (purpose)
• Postmodifier — The non-finite clause modifies a noun or noun phrase, adding descriptive detail.
  • The man wearing a red hat is my uncle.
• Noun phrase function — The non-finite clause replaces a traditional noun as a nominal element.
  • Smoking is harmful to your health. (gerund clause functioning as a noun)

Notice that the subject function and the noun phrase function overlap quite a bit. A gerund clause acting as a subject is functioning as a noun phrase. The distinction matters most when you're identifying clause roles on an exam: ask yourself whether the non-finite clause is doing the job of a noun, an adjective, or an adverb.

Non-finite clauses as sentence elements

This section zooms in on the three nominal functions: subject, object, and complement.

Subject function

Both infinitive and gerund clauses can serve as subjects, but they aren't always interchangeable.

• Gerund clauses as subjects tend to sound more natural in everyday English: Exercising regularly improves health.
• Infinitive clauses as subjects often sound more formal: To travel the world is her dream. In casual writing, you'll more commonly see this rephrased with "it" as a dummy subject: It is her dream to travel the world.

Object function

• Direct object: The non-finite clause receives the action of the verb. She loves to sing in the shower. Which verbs take gerunds, which take infinitives, and which take both is one of the trickiest parts of English grammar. Verbs like enjoy, avoid, and finish take gerunds. Verbs like want, decide, and hope take infinitives. Verbs like love, like, and prefer can take either.
• Indirect object role: Less common, but some constructions place a non-finite clause in an indirect-object-like position. The teacher assigned us to write an essay. Here, "us" is the indirect object and "to write an essay" is the direct object (an infinitive clause).

Complement function

• Subject complement: Follows a linking verb and describes the subject. His ambition is to become a pilot. The linking verb "is" connects "his ambition" to the infinitive clause.
• Object complement: Provides additional information about the direct object. We considered him to be trustworthy. Here "to be trustworthy" tells you more about "him."

Non-finite clauses as modifiers

When non-finite clauses modify nouns or adjectives, they work much like adjectives or relative clauses.

Postmodifier function

A postmodifier sits right after the noun it describes.

• Infinitive clauses often express purpose or potential: She needs a place to stay. ("to stay" tells you what kind of place)
• Present participle clauses describe an ongoing action: The children playing in the park are my neighbors. ("playing in the park" identifies which children)
• Past participle clauses indicate a completed action or passive meaning: The package delivered yesterday was damaged. ("delivered yesterday" tells you which package)

Adjective modification

Non-finite clauses can also modify adjectives, not just nouns.

• She was happy to help with the project. The infinitive clause "to help with the project" specifies why or in what way she was happy.
• The dog lying on the porch looks friendly. The participle clause modifies "dog," which in turn is described by "friendly."

Reduced relative clauses

Many non-finite postmodifiers are actually shortened versions of full relative clauses. Recognizing this helps you understand the structure:

• The man speaking to the crowd is the mayor. → Full form: The man who is speaking to the crowd is the mayor.
• The package delivered yesterday was damaged. → Full form: The package that was delivered yesterday was damaged.

You can reduce a relative clause to a non-finite clause when the relative pronoun is the subject of the relative clause. Just drop the pronoun and any auxiliary verb.

Application of non-finite clauses

Knowing the functions is one thing. Using non-finite clauses correctly in your own writing takes some practice. Here are the main areas to watch.

Proper placement

The most common error with non-finite clauses is the dangling modifier, where the non-finite clause doesn't clearly attach to the right noun.

• Incorrect: Walking down the street, a cat crossed my path. (This says the cat was walking down the street.)
• Correct: Walking down the street, I saw a cat cross my path.

The rule: the implied subject of the non-finite clause must match the subject of the main clause. If it doesn't, you have a dangling modifier.

Choosing infinitives vs. gerunds

• Some verbs require one or the other: She enjoys swimming (not to swim). She decided to leave (not leaving).
• Some verbs change meaning depending on the form: He stopped smoking (he quit) vs. He stopped to smoke (he paused in order to smoke).
• Present participles describe ongoing or simultaneous actions (the running water), while past participles describe completed or passive states (the written letter).

Maintaining parallelism

When you list non-finite clauses, keep them in the same form.

• Correct: He enjoys hiking, camping, and fishing. (all gerunds)
• Incorrect: He likes swimming, biking, and to run. (mixed forms)

Punctuation rules

1. Introductory non-finite clauses get a comma: Having finished dinner, we went for a walk.
2. Restrictive modifiers (essential to identifying the noun) get no commas: The woman wearing a red dress is my sister. (Which woman? The one in red.)
3. Non-restrictive modifiers (extra information, not essential) get commas: My sister, wearing a red dress, arrived late. (You already know which sister; the clause just adds detail.)

Recognizing and correcting common errors

• Misplaced modifiers: Place the non-finite clause as close as possible to the word it modifies.
• Faulty parallelism: Keep all items in a list in the same grammatical form.
• Unclear references: Make sure the implied subject of the non-finite clause is obvious. After writing the email, it was sent immediately is unclear because "it" doesn't tell you who sent the email. Better: After writing the email, she sent it immediately.