necessarily

Necessarily is an adverb that expresses inevitability, certainty, or logical consequence. It can modify verbs, clauses, or entire propositions to indicate that something must be the case, or that a conclusion follows from what has been stated. In ordinary usage, it often hedges a claim by signaling that the statement holds under the stated assumptions, rather than universally in all possible circumstances.

Etymology: The adverb derives from the adjective necessary, which comes from Latin necessarius, from necessitas “necessity.”

Logic and philosophy: In these fields, necessarily signals truth in all possible worlds. A proposition is necessarily true if it is true in every possible world. This notion is a central part of modal logic, where necessity is contrasted with possibility. The use of necessarily helps distinguish between what follows from given premises and what holds only in the actual or contingent world.

Usage and examples: In mathematics, 2+2=4 is necessarily true. In argument, if all humans are mortal and Socrates is a human, then Socrates is mortal (within the framework of those premises, the conclusion follows necessarily). In everyday language, not necessarily indicates that a claim is not guaranteed or required: being wealthy does not necessarily ensure happiness.

Notes: The term is common across disciplines, from everyday speech to formal logic. Its precise force depends on the context—common usage often signals logical consequence under certain assumptions, rather than an absolute universal truth.