"To boldly go where no man has gone before." If you're a fan of Star Trek, you know this famous line. But did you know it contains what strict traditional grammarians consider a major error? It uses a split infinitive. In this advanced grammar lesson, we will explore the fascinating world of infinitives, when to drop the "to" (bare infinitives), and whether splitting them is really a grammatical crime.

The Rule

An infinitive is the base form of a verb. It appears in two forms in English:

  • TO-infinitive: includes the marker "to" (e.g., to go, to understand, to run).
  • Bare infinitive: omits the "to" (e.g., go, understand, run).

1. When to Use the Bare Infinitive

While the TO-infinitive is more common (acting as a noun, adjective, or adverb of purpose), the bare infinitive is strictly required in specific grammatical structures.

A. After Modal Verbs

Always use a bare infinitive after modal auxiliaries like can, could, will, would, shall, should, may, might, must, and the modal use of need.

Examples

✅ We must submit the report by 5 PM.
❌ We must to submit the report.

B. After Causative Verbs (Make and Let)

As discussed in our causative verbs lesson, make and let take a bare infinitive.

✅ They let him leave early.

C. After Perception Verbs

Verbs of perception (see, hear, feel, watch, notice, observe) can take a bare infinitive to indicate that you witnessed the entire completed action.

Examples

✅ I saw her leave the building. (I saw the whole event.)
✅ I saw her leaving the building. (I saw her in the middle of the action - present participle.)

D. Special Phrases

Phrases like had better, would rather, need not, and dare not take the bare infinitive.

✅ You had better apologize.
✅ I would rather stay home.

2. When to Use the TO-Infinitive

The TO-infinitive is used in most other scenarios:

  • To express purpose: I went to Delhi to attend a conference.
  • After certain verbs: want, hope, decide, plan, agree (e.g., I decided to resign.)
  • After adjectives: happy, eager, ready (e.g., I am happy to help.)
  • After nouns: ability, decision, attempt (e.g., Her ability to cope is impressive.)

3. The Split Infinitive Debate

A split infinitive occurs when an adverb is placed between "to" and the verb (e.g., to boldly go, to better understand).

The Historical Rule

In the 19th century, grammarians decided English should follow Latin rules. In Latin, an infinitive is a single word (e.g., ire = to go) and therefore cannot be split. They applied this logic to English and declared split infinitives incorrect.

Modern Acceptance

Today, almost all major style guides and linguists agree: split infinitives are grammatically perfectly fine in contemporary English. In fact, sometimes failing to split an infinitive creates awkwardness or ambiguity.

Clarity Matters

Consider the difference in meaning:

✅ I want to really understand quantum physics. (My understanding will be deep.)
✅ I really want to understand quantum physics. (My desire is very strong.)

In this case, splitting the infinitive is the only way to convey the exact meaning clearly!

4. Style Advice

  • Everyday and Journalistic Writing: Splitting infinitives is completely acceptable and often sounds more natural.
  • Very Formal/Academic Writing: If you have strict professors or are submitting to conservative journals, you may choose to avoid splitting infinitives to prevent unnecessary criticism.

5. Common Mistakes to Avoid

Watch Out!

❌ He can to speak French. (Using TO after a modal)
✅ He can speak French.

❌ I want go home. (Using bare infinitive after want)
✅ I want to go home.

✏️ Quick Practice — Infinitives in Action

  1. She should _____ (to apologize / apologize) immediately.
  2. I heard the bomb _____ (explode / to explode) from miles away.
  3. Is this a split infinitive? "We need to carefully analyze the data."

Answers: 1. apologize (modal rule)  |  2. explode (perception verb rule)  |  3. Yes ("carefully" is between "to" and "analyze").

Summary

  • Use bare infinitives after modals, causatives (make/let), perception verbs, and phrases like would rather.
  • Use TO-infinitives for purpose, and after most standard verbs, adjectives, and nouns.
  • Splitting infinitives (inserting an adverb after "to") is acceptable in modern English and often necessary for clarity.