Mastering the Five Functional Uses of Infinitives in English

In this lesson, Alex provides a comprehensive guide on how to utilize infinitives—defined as "two plus the base verb" (e.g., to run, to eat)—within English sentences. While infinitives represent actions, they frequently function grammatically as nouns. The following breakdown outlines the five distinct ways to incorporate them into your speech and writing.

1. Infinitives as Subjects

Infinitives can serve as the subject of a sentence, though this is considered a "very formal structure." Examples include "To do the right thing is not easy" or "To learn a new language is helpful."

In natural, everyday conversation, native speakers rarely use this structure. Instead, they prefer the "it phrase" construction to maintain a more conversational tone. For instance, rather than starting with the infinitive, one would say, "It's not easy to do the right thing" or "It's helpful to learn a new language."

2. Infinitives as Objects

Infinitives frequently function as the object of a verb. This is common in everyday English. In the sentence "I want to help you," the verb "want" is followed by the infinitive "to help," which acts as the object. Similarly, in the phrase "They love to travel," the infinitive serves as the direct object of the verb "love."

3. Infinitives as Subject Complements

A subject complement provides additional information about the subject of the sentence. When we use infinitives in this capacity, we are clarifying or defining the subject. For example, in the sentence "Her job is to assist you," the infinitive "to assist" explains the nature of "her job." Likewise, "My dream is to open a business" uses the infinitive to provide specific detail about "my dream."

4. Infinitives as Adjectives (Object Complements)

While it may seem counterintuitive to label an infinitive as an adjective, they function as such by describing or modifying an action. Alex suggests viewing these as "object complements." In the sentence "I told you to wait," the phrase "to wait" describes exactly what the speaker told the listener to do. Similarly, in "He wants me to leave," the infinitive "to leave" describes the desire or request directed at the object ("me").

5. Infinitives as Adverbs

Adverbs provide extra information about a verb. In this context, infinitives explain the purpose or reasoning behind an action. For instance, in "We must study to learn," the infinitive "to learn" explains why the action of studying is necessary. Furthermore, in the sentence "I want to learn to sing," the infinitive "to sing" modifies the preceding verb to explain the specific goal of the learning process.

Conclusion: Fluency over Technicality

Alex emphasizes that while understanding these grammatical categories—subject, object, complement, adjective, and adverb—is useful, it is not strictly necessary for daily communication. The primary goal is comprehension and correct usage. As long as you understand the meaning behind sentences like "We must study to learn" and can apply these structures fluidly, you have mastered the essential components of using infinitives in English.