Infinitives that Show "Purpose" or "Reason"
Sometimes an infinitive clause occurs in a sentence to express a "purpose" or a "reason." In such cases, it is often preceded by the words in order to, as in the following sentences.
In order § to improve the application, the software engineer removed some of the unnecessary features.
The software engineer removed some of the unnecessary features in order § to improve the application.
The infinitive clause, in order to improve the application, explains the reason why the software engineer removed some of the unnecessary features. In the first sentence, the infinitive clause precedes the main clause; in the second sentence, it follows the main clause.
In these kinds of sentences, the logical subject of the infinitive is generally interpreted to be the subject of the main clause, irrespective of the properties of the finite verb in the main clause. In each of the above sentences, the software engineer, which is the subject of the main clause, is interpreted as the logical subject of to improve. That is, the software engineer not only removed some of the unnecessary features, but also improved the application.
Sometimes an infinitive clause is not preceded by in order to but still expresses a purpose or reason:
§ to improve the application, the software engineer removed some of the unnecessary features.
The software engineer removed some of the unnecessary features § to improve the application.
These sentences are interpreted exactly the same as the sentences in which in order to precedes the infinitive clause.
Sometimes an infinitive clause expressing a purpose or reason will occur in a sentence in which the main verb is passive:
The technicians were fired by the management in order § to reduce costs.
In such cases, the logical subject of the infinitive is generally not the subject of the main clause but is the object of the by-phrase. Thus, in the sentence above, the logical subject of to reduce is the management. If such a passive sentence has no by-phrase, the logical subject is interpreted from the context, for example, as the object of a by-phrase if there were one:
The technicians were fired in order § to reduce costs.
In this sentence, whoever was responsible for firing the technicians would be interpreted as the logical subject of to reduce.