An infinitive is the base form of a verb, like "learn," often with "to" (e.g., "to learn") or without (e.g., "learn"). This flexible form can act as a noun, adjective, adverb, and more. This article explores the types of infinitives, their uses, examples, and key details to help you master them.
What Is an Infinitive?
An infinitive is a verb’s basic, dictionary form that shows an action or state without linking to a subject or tense. English has two types: full infinitives ("to" + verb, like "to dance") and bare infinitives (just the verb, like "sing"). They don’t change for person, number, or tense but can serve as nouns, adjectives, or adverbs.
In Old English, infinitives often ended in "-an" (e.g., "singan" for "to sing"). Today’s simpler form keeps their versatility alive.
Basic Examples
- Full infinitive: To travel is my dream.
- Bare infinitive: She must try harder.
Types of Infinitives
English infinitives are split into two main categories, each with distinct uses.
Full Infinitives (To-Infinitives)
A full infinitive includes "to" before the base verb (e.g., "to write"). It’s the more common type and often follows verbs of intention, desire, or necessity.
Examples
- She hopes to succeed in her exams.
- I plan to visit Japan next year. (Correct)
- I plan visit Japan next year. (Incorrect—needs "to")
Certain verbs, like "want," "need," "decide," and "promise," always pair with full infinitives when followed by another verb.
Bare Infinitives (Zero Infinitives)
A bare infinitive is just the base verb without "to" (e.g., "run"). It’s less common and typically appears after modal verbs (e.g., "can," "must"), verbs of perception (e.g., "see," "hear"), or causative verbs (e.g., "make," "let").
Examples
- You should go now. (After modal "should")
- I heard him sing beautifully. (After perception verb "hear")
- They let us leave early. (After causative "let")
Quick Test: After modals, the verb stays bare and doesn’t change with the subject: "I can swim" → "She can swim" (infinitive), versus "I swim" → "She swims" (not an infinitive).
Infinitive Phrases
An infinitive paired with objects, complements, or modifiers form an infinitive phrase (e.g., "to read a book quietly"). These phrases can act as nouns, adjectives, or adverbs, just like single infinitives, and apply to both full and bare forms.
Examples
- To bake a cake for the party takes time. (Full infinitive phrase as subject)
- She trains to improve her skills daily. (Full infinitive phrase as adverb)
- He must finish the project by Friday. (Bare infinitive phrase after modal)
Functions of Infinitives
Infinitives are grammatical multitaskers. Here’s how they work in sentences, with examples for clarity.
As a Subject (Noun)
Full infinitives can act as the subject, treating the action as a concept. This use is often formal.
Examples
- To forgive is divine.
- To learn new languages requires dedication.
As an Object (Noun)
Full infinitives often serve as direct objects after verbs like "want," "love," or "try."
Examples
- He loves to dance at parties.
- We agreed to meet later.
As a Subject Complement (Noun)
After linking verbs (e.g., "be," "seem"), infinitives can describe the subject.
Examples
- Her goal is to win the race.
- This appears to be a mistake.
As an Adverb (Modifier)
Infinitives can modify verbs, explaining purpose, result, or reason. Replace "to" with "in order to" to test this use.
Examples
- She studies to pass her exams. (Purpose)
- He shouted to get attention. (Result)
- Note: To pass her exams, she studies. (Add a comma when starting with an adverbial infinitive.)
As an Adjective (Modifier)
Infinitives can describe nouns, often indicating purpose or quality.
Examples
- A book to read arrived today. (Modifies "book")
- This is the best way to solve the problem. (Modifies "way")
Other Uses
- After Adjectives: It’s hard to believe. (Explains "hard")
- With "Too" or "Enough": He’s too tired to drive. / She’s strong enough to lift it.
- With Questions (Bare Infinitive): Why wait? (Rhetorical or suggestive)
Advanced Infinitive Forms
Infinitives aren’t limited to the simple base form. They can take on complex structures with auxiliary verbs, often overlooked in basic guides.
Perfect Infinitive
"To have + past participle" (e.g., "to have finished") shows a completed action relative to another time.
- I’m glad to have met you. (Before now)
Continuous Infinitive
"To be + present participle" (e.g., "to be running") suggests an ongoing action.
- She seems to be working hard.
Perfect Continuous Infinitive
"To have been + present participle" (e.g., "to have been studying") combines completion and duration.
- He claims to have been writing all day.
Passive Infinitive
"To be + past participle" (e.g., "to be seen") shifts the focus to the receiver.
- The room needs to be cleaned.
Split Infinitives: Myth and Reality
A split infinitive occurs when a word (usually an adverb) separates "to" and the verb (e.g., "to boldly go"). Historically criticized due to Latin’s indivisible infinitives, this "rule" is now widely debunked. Splitting is fine for emphasis or clarity, though rewording can suit formal writing.
Examples
- To quickly finish the task felt great. (Split, informal)
- To finish the task quickly felt great. (Unsplit, neutral)
- She aims to truly understand the issue. (Split for emphasis—best option)
Infinitives vs. Gerunds
Infinitives and gerunds ("-ing" forms like "swimming") overlap as nouns but differ in use. Gerunds are more common as subjects; infinitives feel abstract or formal. Some verbs take one, not the other, or both with nuance.
Examples
- Reading helps me relax. (Gerund, preferred)
- To read helps me relax. (Infinitive, formal)
- I like to swim. / I like swimming. (Both work, slight tone shift)
- I avoid talking. (Gerund only) / I plan to talk. (Infinitive only)
- Preposition Rule: She’s tired of waiting. (Gerund after preposition)
Common Mistakes with Infinitives
Learners often stumble with infinitives. Here’s what to watch for:
- Wrong Form: "I want go" → "I want to go."
- Modal Confusion: "She must to leave" → "She must leave." (Bare after modals)
- Overusing "To": "He made me to do it" → "He made me do it."
Frequently Asked Questions (FAQs)
What’s the difference between full and bare infinitives?
Full infinitives use "to" (e.g., "to eat") and are versatile; bare infinitives skip "to" (e.g., "eat") and follow modals or specific verbs.
Can infinitives show tense?
Yes, through advanced forms like "to have written" (past) or "to be writing" (ongoing).
How do I spot an infinitive phrase vs. a prepositional phrase?
"To" can confuse: "To the park" (preposition + noun) vs. "to run" (infinitive + verb). Check what follows "to."
Why use infinitives instead of gerunds?
Infinitives often imply purpose or potential (e.g., "I study to learn"), while gerunds focus on the action itself (e.g., "Studying is fun").
Are split infinitives wrong?
No, they’re grammatically valid—use them for style or clarity, but rephrase in formal contexts if unsure.
Conclusion
Infinitives, like "to learn" or "learn," are key to English grammar, serving as nouns, adjectives, adverbs, and more. They come in full and bare forms, extend into phrases like "to read a book," and even split for emphasis (e.g., "to boldly go"). From basic uses to advanced forms like "to have been learning," they differ from gerunds and offer flexibility. Mastering their types, uses, and quirks sharpens your writing and speaking skills. Embrace infinitives, and lift your English with ease!