Deductive mood

Epistemic grammatical mood

The deductive mood is an epistemic grammatical mood that indicates that the truth of the statement was deduced from other information, rather than being directly known.^[1] In English, deductive mood is often indicated by the word must, which is also used for many other purposes. By contrast, some other languages have special words or verb affixes to indicate deductive mood specifically.

An example in English:

I can smell gas in the house! Someone must have left the stove on!

(deductive indicated by must)

References

^ Loos, Eugene E.; Susan Anderson; Dwight H. Day, Jr; Paul C. Jordan; J. Douglas Wingate. "What is deductive mood?". Glossary of linguistic terms. SIL International. Retrieved 2022-09-13.

Linguistic modalities and grammatical moods

Realis
(what is)

Indicative/declarative
Aggressive
Energetic
Evidential (Sensory)
Generic/gnomic
Mirative

Irrealis

Deontic (what should be)	Benedictive Commissive (promises, threats) Directive (commands, requests, requirements) Debitive Deliberative Dynamic Hortative (+ subtypes) Imperative Injunctive Jussive Necessitative Permissive Precative Prohibitive Propositive Volitive (hopes, wishes, fears) Desiderative Imprecative Optative
Epistemic (what may be)	(inferences, possibilities, questions, etc.) Alethic Assumptive Deductive Dubitative Hypothetical Inferential/renarrative/oblique Interrogative Potential Speculative Subjunctive
Dependent circumstances (what would be)	Conditional Eventive