2.5.3 Understood if clauses

Rule: In conditional sentences where the if clause is understood but not expressed, the tense usage in the main clause is the same as in other conditional sentences.

Examples of errors:

1. We cannot reject industrial society; we must use it to develop alternative ways of living. Otherwise we had to give up our living standard.
2. The teacher could recommend reading Max Frisch's books, so that the students are impelled to reflect on their own problems.
3. So one task of the government should be to subsidize the development of a technology that makes it possible to use solar power.
4. It should be possible to get a map that helps all the students.
5. I suggest founding a committee which collects the suggestions of the student's.
6. I would deal with it carefully in order to avoid damage which can't be repaired afterwards.

It is convenient to analyze sentences like those above as special cases of unreal conditions, since a suppressed or understood if clause is easily recoverable:

1. if we do/did reject it...
2. if the teacher recommends/recommended them...
3. if such a technology is/were developed
4. if such a map is/were available...
5. if such a committee were/was founded
6. ...if such damage occurs/occurred

Whether these conditional sentences are considered real or unreal depends on the speaker's attitude concerning the likelihood of the (suppressed) condition. (2)-(4) and (6) would more likely be considered unreal conditions,' since the use of should or could in the matrix clause--i.e. the main clause in which the (main) conditional clause is embedded--already indicates that the speaker is considering relatively hypothetical possibilities. The rules that are violated in such sentences, then, are the same as those for tense usage in real and unreal conditions with expressed if clauses (cf. 2.5.1-2).