Purpose clauses

8.43 When you want to indicate the purpose of an action, you use a purpose clause.

Here is a list of the most common conjunction used in purpose clauses:

in order that in order to

so so as to

so that to

types of purpose clause 8.44 There are two kinds of purpose clause.

Non-finite purpose clauses are the most common kind. They contain a 'to'-infinitive.

They had to take some of his land in order to extend the churchyard.

Farmers have put up barricades to prevent hippies moving on to their land.

The subject of a non-finite purpose clause is always the same as the subject of the main clause.

Non-finite purpose clauses are explained in paragraphs 8.45 to 8.46.

Finite purpose clauses usually contain a 'that'-clause.

Be as clear and factual as possible in order that there may be no misunderstanding.

Finite purpose clauses are explained in paragraphs 8.47 to 8.48.

8.45 Non-finite purpose clauses usually begin with 'in order to' or 'so to'.

They were shoving each other out of the way in order to get to the front.

They have tried to limit such imports in order to protect their members jobs.

The best thing to do is to fix up a screen so as to let in the fresh air and keep out the flies.

If you want to make one of these clauses negative, you put 'not' in front of the 'to'.

Rose trod with care in order not to spread the dirt.

When removing a stain, work from the edge inwards so as not to enlarge the area affected.

6.46 Non-finite purpose clauses can simply be 'to'-infinitive clauses.

People would stroll down the path to admire the garden.

The children sleep together to keep warm.

To understand what is happening now, we need to reflect on what has been achieved in the last decade.

However, you cannot use a negative with one of these structures. You cannot say, for example, 'We keep the window shut not to let the files in'. You would have to say, 'We keep the window shut in order not to let the flies in'.

8.47 Finite purpose clauses usually begin with 'in order that', 'so that', or 'so'. They usually contain a modal.

If the verb in the main clause is in a present tense or in the present perfect tense, you usually use one of the modals 'can', 'may', 'will', or 'shall' in the purpose clause.

It's best to be as short, clear and factual as possible, in order that there may be no misunderstanding.

...people who are teaming English in order that they can study a particular subject.

If the verb in the main clause is in a past tense, you usually use 'could', 'might', 'should', or 'would' in the purpose clause.

A stranger in the crowd had hoisted Philip up on his shoulder so that he might see the procession depart.

I bought six cows so that we should have some milk to sell.

She said she wanted tea ready at six so she could be out by eight.

Ordinary verbs are occasionally used instead of modals, especially in negative purpose clauses.

Brian would like to increase his son David's wage, so that David doesn't get disillusioned because his contemporaries in less skilled jobs are earning more.

'So that' is also used in result clauses. This use is explained in paragraphs 8.55 and 8.56.

8.48 In formal or old-fashioned English, 'lest' is sometimes used at the beginning of a finite purpose clause to say what an action is intended to prevent.

For example, 'They built a statue of him lest people should forget what he had done' means the same as 'They built a statue of him so that people should forget what he had done'.

He was put in a cell with no clothes and shoes lest he injure himself.

He spoke in whispers lest the servants should hear him.

In clauses beginning with 'lest', you use either the subjunctive mood or a modal.