The Subjunctive

The subjunctive, one of the most important syntactical elements in Persian, has two forms: Subjunctive I (present) and Subjunctive II (past).

The Subjunctive I is formed by the addition of the stressed prefix -ب to the present stem. In the negative, the -ن replaces the subjunctive prefix. The verb بودن as well as most simple verbs having a prefix (such as -بار or -دار) form the subjunctive without -ب. This applies often also to کردن and شدن. For داشتن the Subjuctive II is used in place of the Subjunctive I.

Similar to the prefix of negation for the preterite, the glide -ی- is inserted between the -ب and the present stem if the stem begins with a vowel. But: The use of the subjunctive in Persian differs widely from that in English.

The Subjunctive I is generally used in the following cases: A verb used in a dependent clause is always formed in the Subjunctive. No syntactical distinction is made between modal auxiliaries (can, must, etc.) and other verbs (modifying verbs) governing the dependent clause. Compare the following two verbs < توانستن < توان (to be able to) and اجازه داشتن (to be allowed to): It should be noted that a) both verbs are conjugated, and b) that the subjunctive in the dependent clause does not change when the tense in the main clause is changed: The modal auxiliaries and modifying verbs are normally placed at the beginning of the sentence. However, in principle, any part of the sentence can take their place when it is to be emphasised. The following three verbs may be called modal auxiliary verbs: < خواستن < خواه (to want or wish), < توانستان < توان (can, may or to be able to) and باید (must, should, ought or to have to). The impersonal باید (originally the 3rd person singular of the obsolete infinitive بایستان) does not change its form. For the past tense, the verb مجبور بودن or مجبور شدن (to be forced or obliged to) usually takes its place.
 * 1) In dependent sentences (after modal auxiliary verbs or modifying verbs).
 * 2) In certain subordinate clauses (mainly after some subordinating conjuctions).
 * 3) Alone (often elliptical).

For negative obligation and absence or lack of obligation the form نباید is common for present, often being rendered by 'do not need to', 'do not have to' or 'must not'.

Used in a deductive sense, باید also expresses a rather sure assumption or probability: The Subjuctive I is also used after the adverb شاید ('probably', originally the 3rd person singular of the obsolete verb شایستان): Modifying verbs are mainly compound verbs (among them the impersonal ones) expressing demand, possibility, necessity, expectation, wish, hope, fear, warning, uncertainty, doubt etc. The dependent clause may here be introduced with the conjunction که (that): After subordinating conjunctions, which introduce a conditional or final clause, the verb is used in the subjunctive. This also applies to a number of temporal conjunctions: The use of the subjunctive after a modifying verb also depends on whether a possibility, condition, doubt etc. should be expressed or not. Compare the following examples: If used independently in a main clause, the subjunctive is a way of asking whether one has to do something, or expresses a feeling of surprise, protest, or disbelief, usually being rendered by 'shall' or 'should'. It may also be used (often elliptically) as the so-called jussive, making a suggestion for the hearer to do something, usually being rendered by 'let', 'should' and 'it would be better to': The Subjunctive II is formed with the Past Participle and the Subjunctive I of the verb بودن: In contrast to the Subjunctive I, the Subjunctive II is mainly used if the action (of the dependent verb) happens in the past. Compare: