Bare infinitive

Wolfgang Drescher from Germany writes:

What is the difference between:

President Bush has announced a plan to help prevent the spread of the AIDS virus.

President Bush has announced a plan to help to prevent the spread of the AIDS virus.

The difference is one of form only. There is no difference in meaning.

to-infinitive or bare infinitive

Help is a verb that can be used with or without to and with or without an object before the infinitive. When we use it without an infinitive it sometimes sounds more informal. Compare the following:

• Could you help me to look for my car keys? I can't find them anywhere.
• Could you help me look for my car keys? I can't find them anywhere.
• Would you like to help to cook dinner tonight? It's late and I'm feeling tired.
• Would you like to help cook dinner tonight? It's late and I'm feeling tired.

There are one or two other structures where to-infinitive and the bare infinitive are both possible. Expressions with do or did, such as what I've done or all I did can follow either pattern.

• I hate shopping so what I've done is (to) order a new computer over the Internet.
• All I did was (to) suggest that she should lend him no more money. I didn't insist on it.

When two infinitive structures are connected by and, or or, except or but and than or as, it is normal practice to omit to in the second clause. Compare the following:

• I would like you to tidy the house and (to) wash the dishes before I get home.
• Would you prefer to have a snack now or (to) wait until later before we eat?
• I could find nothing to do this afternoon, except read my book.
  My son does nothing but watch TV when he gets home from school.
• It's quicker to bike to the station rather than take the car.
• I have to fix breakfast for everybody as well as take the children to school before I can leave for work.

Bare infinitive only

Generally speaking, bare infinitive structures are much less common than to-infinitive structures, but after certain verbs they are necessary.

We use the infinitive without to after modal auxiliary verbs will, shall, would, could, can (but not be able to), may, might, must (but not have to), should (but not ought to), and needn't, (but not need to, which behaves like a normal verb). Compare the following:

• I can't agree with you on this, though I would like to be able to help you.
• You must finish your own work before you go out, but you don't have to help your sister.
• It will be hot and sunny today so you should put on plenty of sunscreen and you ought to wear a hat.
• He needn't take time off work, but he needs to rest in the evenings and get a good night's sleep before he sets off on the new expedition.

After the object after certain verbs, such as hear, see, make, let, there is no to:

• I saw him pour the medicine down the loo and I heard him laugh to himself.
• I cannot make you take this medication, I can only ask you to take it.
• I can't let you go to bed hungry. You must let me prepare you some supper.

After verbal idioms would rather and had better there is no to:

• I'd rather swim in the pool than go down to the beach.
  Geoffrey has just driven up in his car. You'd better see what he wants.

All of these, however, represent exceptions to the general rule. Most infinitive structures begin with to:

• I decided to leave work early. I intended to be home before six. And I had arranged to play tennis with Joan in the evening.