Hatav argues that the TAM (Tense-Aspect-Mood) system of a language should be described from Semantics, specifically the truth-condition perspective, rather than Pragmatics. Pragmatic perspectives tend to describe aspect based on the perspective of the speaker, however Hatav argues that it is temporality that is important. This can especially be demonstrated in Biblical Hebrew, which does not specifically mark tense. Tense is only interpreted by the help of adverbs or other context. Especially important are the relative relationships between S(peech)-time, E(vent)-time, and R(eference)-time. R-time represents the relative location of the speaker within the discourse. For example, in “I had seen John (when you called me)” even though the S-time is after the E-time (when you called me), the R-time precedes it. The choice of aspect then is not based on the speaker’s attitude toward the nature of the action, but it is a function of the interval between S-time and R-time and the necessary truth conditions.
Hatav describes three basic aspects: sequence, inclusion, and perfect. A verb marked for sequence (wayyiqtol and wqatal) moves R-time forward. A verb marked for inclusion (progressive) describes a situation which includes its R-time. If the R-time is not the S-time, then it must come from the context or else such a sentence will be ill-formed. A perfect verb is used for anteriority, simultaneity, and backgrounding. The perfect is a “parasitic” aspect, meaning that a clause in the perfect depends on some other situation’s R-time or an explicit adverbial time expression for temporal interpretation.
In BH the yiqtol and wqatal can be used to denote both simple future and past habitual propositions. This is because modality does not follow from R-time relations, but the notion of possible worlds or branching options. Thus conditionals and habituals should be analyzed as modals. Traditionally, modality has been reserved for volitional statements expressing wishes or desires of the speaker (a Pragmatic perspective).