Bare Infinitive: The Complete Guide to Understanding and Using the Base Form Verb

Master the bare infinitive in English grammar with comprehensive coverage of definitions, pronunciation, usage rules, modal verbs, causative constructions, perception verbs, and common mistakes that language learners make

The bare infinitive stands as one of the most fundamental yet frequently misunderstood grammatical structures in English. Unlike its cousin the full infinitive (marked by "to"), the bare infinitive appears without any grammatical marker—simply the base form of the verb standing alone in specific syntactic contexts. This seemingly simple construction plays crucial roles throughout English grammar, appearing after modal auxiliary verbs, in causative constructions, with perception verbs, and in numerous idiomatic expressions. For native speakers, using bare infinitives comes naturally and unconsciously; for language learners, however, knowing when to use "go" versus "to go" represents a persistent challenge that reveals deep structural patterns in English verb phrases. This comprehensive guide explores every dimension of the bare infinitive: its precise definition and grammatical function, correct pronunciation patterns, historical etymology and development, the specific contexts demanding its use, contrasts with full infinitives and other verb forms, common mistakes made by learners and how to avoid them, pedagogical approaches to teaching this structure, and advanced applications in complex sentence constructions. Whether you're a language learner striving for accuracy, a teacher seeking clearer explanations, a linguist analyzing English syntax, or simply a curious mind fascinated by how language works, understanding the bare infinitive illuminates essential patterns governing English verb usage.

Defining the Bare Infinitive: What It Is and How It Works

The bare infinitive (also called the base infinitive or plain infinitive) is the base form of a verb used without the infinitive marker "to." It represents the verb in its simplest, unmarked state—the form you would find listed in a dictionary.

Bare Infinitive Definition:

The base form of a verb appearing without "to" in specific grammatical contexts where English syntax demands or permits this unmarked form.

Examples of Bare Infinitives:

• go (not "to go") - "I must go now."
• eat (not "to eat") - "She can eat anything."
• run (not "to run") - "They should run faster."
• be (not "to be") - "It might be true."
• work (not "to work") - "We let him work alone."

The key distinguishing feature is the absence of "to." While full infinitives combine "to" with the base verb ("to walk," "to think," "to understand"), bare infinitives stand alone as the pure verb form. This distinction matters grammatically because English syntax strictly governs which contexts require bare infinitives versus full infinitives—using the wrong form creates ungrammatical sentences that sound immediately wrong to native speakers.

Grammatical Function and Status

Grammatically, the bare infinitive functions as the main verb in a verb phrase, but it always appears in specific syntactic environments. It cannot stand alone as the main verb of a sentence (you cannot say "*I go tomorrow" meaning future—this requires "will go"). Instead, bare infinitives appear as complements to specific auxiliary verbs, causative verbs, and perception verbs that govern their syntactic behavior.

Key Grammatical Properties:

• Tenseless: Bare infinitives carry no tense marking themselves; tense comes from the auxiliary or main verb governing them
• Unmarked for person/number: The form remains constant regardless of subject ("I/you/he/she/we/they must work")
• Syntactically dependent: Always appears as complement to another verb or construction
• Base form identical: Identical to the dictionary base form of the verb (except "be," which has special forms)

Pronunciation: How to Say Bare Infinitives

The pronunciation of bare infinitives follows the standard pronunciation of the base verb form, which varies considerably across English verbs due to irregular patterns inherited from historical sound changes.

Bare Infinitives: Pronounced as Base Verb Forms

Since bare infinitives are simply the base forms of verbs used in specific contexts, their pronunciation matches the dictionary pronunciation of each verb. However, several pronunciation patterns merit attention:

Regular Verb Patterns

Common Pronunciation Patterns:

• walk /wɔːk/ - "You should walk more."
• help /help/ - "I will help you."
• move /muːv/ - "They must move quickly."
• think /θɪŋk/ - "We can think about it."
• speak /spiːk/ - "She might speak tomorrow."

Irregular and Tricky Pronunciations

Several common bare infinitives have pronunciation features that challenge learners:

• do /duː/ - Stressed vowel, not reduced like in "to do" /tə duː/
• go /ɡəʊ/ (British) or /ɡoʊ/ (American) - Diphthong pronunciation
• be /biː/ - Long vowel sound, distinct from "been" or "being"
• have /hæv/ - Full vowel, not reduced /həv/ as it might be in rapid speech
• read /riːd/ - Present form pronunciation (not past tense /red/)

Stress Patterns with Modal Verbs

When bare infinitives follow modal auxiliary verbs, typical stress patterns place primary stress on the bare infinitive rather than the modal, unless the modal is emphasized:

• Normal stress: "I can GO." (stress on GO)
• Emphatic stress: "I CAN go!" (stress on CAN for emphasis)
• Normal stress: "She should STUDY." (stress on STUDY)

Etymology: The Historical Development of Bare Infinitives

Understanding the etymology of bare infinitives requires examining how English verb systems evolved from Old English through Middle English to Modern English, with the bare infinitive representing a surviving remnant of older grammatical patterns.

Historical Development:

Old English (450-1150): Old English had distinct infinitive forms marked by endings like "-an" (e.g., "sprecan" = to speak, "gān" = to go). The language also had grammatical cases that marked infinitive relationships. Modal verbs (precursors to modern modals) governed infinitives in structures that would eventually lose their explicit markings.

Middle English (1150-1500): During this period, English underwent massive simplification of inflectional endings. The Old English infinitive ending "-an" eroded, eventually disappearing. Simultaneously, the particle "to" (derived from a directional preposition meaning "toward") grammaticalized as an infinitive marker. However, after modal auxiliaries and certain other verbs, the infinitive continued appearing without "to"—essentially, the base form remained unmarked in these contexts.

Early Modern English (1500-1700): The patterns governing bare infinitive usage stabilized into forms recognizable today. Modal auxiliaries had fully grammaticalized into their modern forms, consistently taking bare infinitives. Causative and perception verb patterns also solidified.

Why "Bare" Instead of "To"?

The survival of bare infinitives after modals relates to the historical status of modal verbs. Originally, modals functioned as main verbs taking objects or complements. As they grammaticalized into auxiliary verbs, they retained their ability to take bare complements—verb forms without additional marking. This created the pattern where modals + bare infinitive became the standard construction.

Similarly, causative verbs like "make" and "let," and perception verbs like "see" and "hear," historically took bare complement clauses. This pattern persisted even as "to" became the standard infinitive marker elsewhere in the language.

Essential Contexts Requiring Bare Infinitives

English grammar mandates bare infinitives in specific, well-defined contexts. Understanding these contexts is crucial for grammatical accuracy.

1. After Modal Auxiliary Verbs

This represents the most common and crucial context for bare infinitives. Modal auxiliary verbs express possibility, necessity, permission, ability, and other modalities, and they always take bare infinitives.

Modal Verbs Taking Bare Infinitives:

• can / could: "I can swim." / "She could help."
• may / might: "You may leave." / "It might rain."
• shall / should: "We shall overcome." / "You should rest."
• will / would: "They will arrive." / "I would prefer."
• must: "He must study."

❌ Common Modal Verb Errors:

• ❌ "I can to speak English." → ✅ "I can speak English."
• ❌ "She must to go home." → ✅ "She must go home."
• ❌ "We should to study." → ✅ "We should study."
• ❌ "They might to arrive late." → ✅ "They might arrive late."

The rule is absolute: modal auxiliaries never take "to" before the infinitive. This differs from semi-modal constructions like "ought to," "have to," and "need to," which are not true modal auxiliaries and therefore do take "to."

2. After Causative Verbs: Make, Let, Have

Causative verbs express causing or allowing someone/something to do an action. Several causative verbs take bare infinitives in active voice constructions.

Causative Verbs with Bare Infinitives:

• make (force): "They made him apologize." (forced to apologize)
• let (allow): "She let me borrow her car." (allowed to borrow)
• have (cause to): "I'll have them call you." (cause them to call)

The structure follows the pattern: Subject + causative verb + object + bare infinitive

More Causative Examples:

• "The teacher made us rewrite the essay."
• "Let me explain the situation."
• "He had his assistant prepare the documents."
• "Don't make me laugh!"
• "They won't let us enter without tickets."

Important Note: Passive Voice Exception

In passive constructions with "make," the infinitive takes "to":

• Active: "They made him apologize." (bare infinitive)
• Passive: "He was made to apologize." (full infinitive with "to")

3. After Verbs of Perception

Verbs of perception (seeing, hearing, feeling, etc.) take bare infinitives when describing perceiving the complete action from beginning to end.

Perception Verbs with Bare Infinitives:

• see: "I saw him leave the building." (saw the complete action)
• watch: "We watched them play soccer." (watched the complete activity)
• hear: "Did you hear her sing?" (heard the singing)
• feel: "She felt the house shake." (felt the shaking)
• notice: "He noticed her smile." (noticed the action)

The pattern is: Subject + perception verb + object + bare infinitive

Bare Infinitive vs. Present Participle with Perception Verbs

With perception verbs, English allows both bare infinitives and present participles (-ing forms), but with subtle meaning differences:

• Bare infinitive (complete action): "I saw him cross the street." (saw the entire action from start to finish)
• Present participle (action in progress): "I saw him crossing the street." (saw him in the middle of crossing)
• Bare infinitive: "We heard the door close." (heard the complete closing)
• Present participle: "We heard the door closing." (heard it in the process of closing)

4. After "Help"

The verb "help" uniquely accepts both bare infinitives and full infinitives with "to," with bare infinitives being more common in American English.

• ✅ "Can you help me move this table?" (bare infinitive—more common in American English)
• ✅ "Can you help me to move this table?" (full infinitive—more formal, more common in British English)
• ✅ "She helped him understand the concept." (bare infinitive)
• ✅ "She helped him to understand the concept." (full infinitive)

5. In the Expression "Had Better"

The semi-modal expression "had better" (often contracted to "'d better") takes a bare infinitive to express strong advice or warning.

• "You'd better hurry up!"
• "We had better leave now."
• "He'd better apologize soon."
• "They had better not be late."

6. After "Why" in Rhetorical Questions

In rhetorical questions beginning with "why," especially "why not," bare infinitives often appear:

• "Why wait any longer?"
• "Why not try something new?"
• "Why bother arguing?"
• "Why not start today?"

Contrasting Bare Infinitives with Other Verb Forms

Understanding bare infinitives requires distinguishing them from related grammatical forms that learners commonly confuse.

Bare Infinitive vs. Full Infinitive (with "to")

Key Differences:

• After modals: Always bare infinitive ("can go," never "can to go")
• After most other verbs: Full infinitive ("want to go," "need to study," "hope to win")
• As subject: Full infinitive ("To err is human," not "*Err is human")
• After causatives: Bare infinitive in active voice ("made him leave"); full infinitive with "make" in passive ("was made to leave")

Bare Infinitive vs. Present Tense

The bare infinitive looks identical to the present tense base form, but they function differently:

• Present tense: "I walk to school every day." (main verb, shows habitual action)
• Bare infinitive: "I can walk to school." (complement after modal, shows ability)
• Present tense: "They study hard." (main verb)
• Bare infinitive: "They must study hard." (complement after modal)

Bare Infinitive vs. Imperative

Imperatives (commands) also use the base verb form but function as independent sentences:

• Imperative: "Close the door!" (command as main clause)
• Bare infinitive: "Please let me close the door." (complement after "let")
• Imperative: "Listen carefully." (command)
• Bare infinitive: "You should listen carefully." (complement after modal)

Common Mistakes with Bare Infinitives

Language learners frequently make predictable errors with bare infinitives, often transferring patterns from their native languages or overgeneralizing English rules.

Mistake 1: Adding "to" After Modal Verbs

Most Common Error:

Many learners incorrectly add "to" after modal verbs because full infinitives are common elsewhere in English.

• ❌ "I must to finish my homework."
• ✅ "I must finish my homework."
• ❌ "She can to speak three languages."
• ✅ "She can speak three languages."
• ❌ "We should to leave early."
• ✅ "We should leave early."

Mistake 2: Confusing "Help" Patterns

Because "help" accepts both forms, learners sometimes use incorrect patterns with other verbs:

• ❌ "She wants go home." (incorrect bare infinitive)
• ✅ "She wants to go home." (needs full infinitive)
• ❌ "They decided leave early." (incorrect bare infinitive)
• ✅ "They decided to leave early." (needs full infinitive)

Mistake 3: Omitting "to" with Non-Modal Verbs

Learners sometimes incorrectly use bare infinitives after verbs that require full infinitives:

• ❌ "I hope see you soon."
• ✅ "I hope to see you soon."
• ❌ "They plan visit Paris."
• ✅ "They plan to visit Paris."
• ❌ "She promised call me."
• ✅ "She promised to call me."

Mistake 4: Using Bare Infinitives as Sentence Subjects

Unlike some languages, English doesn't allow bare infinitives as subjects:

• ❌ "Learn English is important."
• ✅ "To learn English is important." OR "Learning English is important." (gerund)
• ❌ "Exercise regularly keeps you healthy."
• ✅ "To exercise regularly keeps you healthy." OR "Exercising regularly keeps you healthy."

Mistake 5: Forgetting "to" in Passive Causatives

Learners often forget that passive constructions with "make" require "to":

• ❌ "He was made apologize."
• ✅ "He was made to apologize."
• ❌ "They were made work overtime."
• ✅ "They were made to work overtime."

Teaching Bare Infinitives: Pedagogical Approaches

For teachers and learners, understanding effective strategies for mastering bare infinitives accelerates grammar acquisition.

Strategy 1: Learn Modal Patterns First

💡 Teaching Tip:

Focus first on modal + bare infinitive patterns, as these are most frequent and follow absolute rules. Create the firm association:

Modal verb = NO "to"

Practice with high-frequency modals: can, will, should, must, might, could, would, may

Strategy 2: Create Contrast Drills

Explicit comparison helps learners recognize pattern differences:

• "I want to go." (full infinitive) vs. "I must go." (bare infinitive)
• "She needs to study." (full infinitive) vs. "She should study." (bare infinitive)
• "We hope to win." (full infinitive) vs. "We can win." (bare infinitive)

Strategy 3: Use Categorization Charts

Organize verbs by what follows them:

Always Bare Infinitive: can, could, may, might, shall, should, will, would, must, make (active), let, perception verbs

Always Full Infinitive ("to"): want, need, hope, plan, decide, expect, promise, agree, refuse, offer

Both Possible: help (regional variation)

Strategy 4: Contextualized Practice

Rather than isolated drill, use bare infinitives in meaningful communication tasks:

• Giving advice: "You should exercise more." / "You'd better rest."
• Describing abilities: "She can play piano." / "They can't swim."
• Making predictions: "It will rain tomorrow." / "They might arrive late."
• Reporting observations: "I saw him leave." / "We heard them argue."

Advanced Applications and Complex Structures

Beyond basic patterns, bare infinitives appear in sophisticated grammatical constructions that advanced learners should master.

Bare Infinitives in Conditional Structures

Modal auxiliaries in conditional sentences take bare infinitives:

• "If I could change one thing, I would."
• "She would help if she could afford it."
• "What would you do if you could travel anywhere?"

Bare Infinitives in Perfect Modal Constructions

When modals combine with perfect aspect ("have" + past participle), "have" appears as a bare infinitive:

• "She must have left already." (bare infinitive "have" after modal)
• "They should have studied harder." (bare infinitive "have")
• "He might have forgotten the appointment." (bare infinitive "have")
• "You could have told me!" (bare infinitive "have")

Multiple Bare Infinitives in Coordination

When coordinating multiple actions after a modal or causative verb, all infinitives remain bare:

• "You should eat well, exercise regularly, and sleep enough."
• "She can read, write, and speak Japanese fluently."
• "They made us clean the kitchen, wash the dishes, and take out the garbage."

Bare Infinitives with Emphatic "Do"

The emphatic auxiliary "do/does/did" takes bare infinitives in affirmative statements:

• "I do understand your concern." (emphatic—bare infinitive "understand")
• "She does work hard." (emphatic—bare infinitive "work")
• "They did arrive on time." (emphatic—bare infinitive "arrive")

Cross-Linguistic Perspectives

Understanding how different languages handle equivalent structures illuminates why English bare infinitives challenge learners.

Language Transfer Issues:

• Romance languages (Spanish, French, Italian): Modal-like verbs often take full infinitives, causing learners to incorrectly add "to" after English modals
• Germanic languages (German, Dutch): Closer patterns to English, but placement and word order differences create challenges
• Asian languages (Japanese, Korean, Chinese): Fundamentally different verb systems; learners must build infinitive concepts from scratch
• Slavic languages (Russian, Polish): Aspectual systems differ dramatically; infinitive concepts don't map directly

Practical Mastery: Exercises and Self-Testing

To achieve fluency with bare infinitives, learners should practice recognizing and producing correct forms in varied contexts.

Self-Check Questions

💡 Ask Yourself:

• Is there a modal verb? If yes → use bare infinitive (no "to")
• Is it make/let/have (causative)? If yes → use bare infinitive in active voice
• Is it see/hear/watch/feel (perception)? If yes → bare infinitive (complete action) or -ing (action in progress)
• Is it any other verb? If yes → probably needs full infinitive with "to" (check specific verb patterns)

Recognition Practice

Train yourself to quickly identify whether contexts require bare or full infinitives:

Which is correct?

• "I would like (go / to go) home." → to go (full infinitive after "would like")
• "You must (finish / to finish) this today." → finish (bare infinitive after modal "must")
• "She let him (borrow / to borrow) her car." → borrow (bare infinitive after causative "let")
• "We decided (leave / to leave) early." → to leave (full infinitive after "decided")

Conclusion: Mastering the Bare Infinitive

The bare infinitive, despite its deceptively simple appearance as merely the base form of a verb, represents a sophisticated grammatical structure whose correct usage distinguishes proficient English speakers from learners still developing full command of the language. Understanding when to use bare infinitives versus full infinitives requires internalizing specific syntactic patterns—modal auxiliaries always demand bare infinitives, causative verbs in active voice take bare infinitives, perception verbs accept bare infinitives for completed actions, and numerous other contexts follow their own specific rules.

For language learners, mastering bare infinitives means moving beyond simple memorization to develop an intuitive feel for English verb phrase structures. This comes through extensive exposure to authentic English, focused practice on high-frequency patterns (especially with modal verbs), awareness of common errors (particularly adding unnecessary "to" after modals), and deliberate attention to the systematic nature of these patterns. Native speakers navigate bare infinitive usage unconsciously; learners must build this automaticity through conscious practice that eventually becomes unconscious competence.

From a broader linguistic perspective, bare infinitives showcase how historical language change creates grammatical patterns that seem arbitrary to outsiders but follow logical principles within the language system. The fact that modals take bare infinitives reflects their historical development as a special class of auxiliary verbs. The causative and perception verb patterns preserve older syntactic structures that persist despite broader changes in English infinitive marking. Understanding these patterns connects individual grammatical rules to the larger story of how English evolved and continues to function as a living, systematic form of human communication.

💡 Final Mastery Checklist:

• ✅ I consistently use bare infinitives after all modal verbs without adding "to"
• ✅ I recognize causative constructions (make/let/have) and use bare infinitives appropriately
• ✅ I understand when perception verbs take bare infinitives versus present participles
• ✅ I know that "help" accepts both bare and full infinitives
• ✅ I remember that passive constructions with "make" require full infinitives
• ✅ I can distinguish bare infinitives from other verb forms (present tense, imperatives)
• ✅ I understand the historical development and systematic nature of bare infinitive patterns

Whether you're a dedicated language learner striving for accuracy, a teacher developing clearer explanations for your students, a linguist analyzing English syntax, or simply someone fascinated by how grammar works, understanding bare infinitives opens windows into fundamental patterns governing English communication. These patterns, once mastered, enable more sophisticated expression, clearer communication, and deeper appreciation for the elegant complexity underlying even the simplest-seeming grammatical structures. The bare infinitive—just the base verb, standing alone without markers—carries within it centuries of linguistic history, systematic grammatical relationships, and the ongoing challenge and beauty of human language itself.