Bare infinitive

It’s not so easy to know when and why you need to use the bare infinitive (run, joke, make etc.), a gerund or ‘to’ + infinitive, and whether or not it is correct. So, there are three rules as to why we use the bare infinitive (infinitive without ‘to’ or –ing):

When to use bare infinitives in English

1. The bare infinitive is used after modal auxiliary verbs (helping verbs: can & could, may & might, will & shall, must, would, ought to & should, need to, dare to).
2. We use the bare infinitive after many verbs or perception, verbs used to perceive. (see, notice, hear etc.).
3. We use the bare infinitive with ‘why’ Interrogatives; wh-? words and how?

We use the bare infinitive after modal auxiliary verbs

However, we do not use the bare infinitive after need to, dare to and ought to, due to their nature (these modal auxiliaries are connected to ‘to’): 

Can	I can tell you where he is if you like.
Could	They could know.
May	She may head out to the party tonight.
Might	Sophie might understand it better.
Will	Will you please be quiet?
Shall	They shall know by tomorrow.
Must	Harry, you must not cross a red light!
Would	Would you be able to help me?
Should	George should definitely run the marathon.
Ought to	* You ought to know what he said.
Need to	*Sir. please, you need to listen to him.
Dare to	*They dared me to jump off.

We use the bare infinitive after many verbs of perception, verbs used to perceive.

These verbs of perception can also take the gerund form:

Watch	I watched you leave/leaving yesterday.
See	I didn’t see you work/working.
Hear	Harry can hear me speak/speaking.
Notice	I notice you quarrel a fair bit.
Feel	I felt you check/checking my ears.
Sense	I sensed them come/coming.
Smell	The dog can smell you eat/eating.

We use the bare infinitive with ‘why’

Why did you leave so early last night?

Why go now?

Why not learn to sail?

Why write when you can type?

Why have I not seen you before?

See also