Protasis

Protasis is a grammatical term referring to the initial clause of a conditional sentence that states the condition under which the action in the main clause (the apodosis) will or would occur. The word comes from Greek protasis, meaning “placing before,” contrasted with apodosis, the clause that expresses the result.

In many languages the protasis is a subordinate clause, often introduced by a conjunction such as if, when, unless, or by a marked form of mood or tense. The specific mood and tense used in the protasis, and in the apodosis, vary with the type of conditional being expressed.

There are several broad types of conditionals. Real or open conditionals present a likely or possible scenario and its result, as in English: “If it rains, we will stay indoors.” Unreal or counterfactual conditionals describe hypothetical or contrary-to-fact situations, as in “If I were rich, I would travel.” In these cases the protasis and apodosis may employ different moods or tenses to reflect reality, possibility, or irreality.

In classical languages, protasis and apodosis form distinct grammatical structures, with specific conventions for tense, mood, or aspect in each part. Beyond formal grammar, the concept is also used in rhetoric and discourse analysis to discuss how a hypothetical scenario is proposed and then followed by its consequence.

In summary, protasis is the opening, condition-expressing clause of a conditional sentence, whose interaction with the apodosis yields the overall conditional meaning.