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In logic and mathematics, necessity and sufficiency are terms used to describe a conditional or implicational relationship between two statements.For example, in the conditional statement: "If P then Q", Q is necessary for P, because the truth of Q is guaranteed by the truth of P.
Necessary and sufficient condition, in logic, something that is a required condition for something else to be the case; Necessary proposition, in logic, a statement about facts that is either unassailably true (tautology) or obviously false (contradiction) Metaphysical necessity, in philosophy, a truth which is true in all possible worlds
Metaphysical necessity is contrasted with other types of necessity. For example, the philosophers of religion John Hick [2] and William L. Rowe [3] distinguished the following three: factual necessity (existential necessity): a factually necessary being is not causally dependent on any other being, while any other being is causally dependent on it.
Modal logic is a kind of logic used to represent statements about necessity and possibility.It plays a major role in philosophy and related fields as a tool for understanding concepts such as knowledge, obligation, and causation.
Contingency is one of three basic modes alongside necessity and possibility. In modal logic, a contingent statement stands in the modal realm between what is necessary and what is impossible, never crossing into the territory of either status. Contingent and necessary statements form the complete set of possible statements.
In economics, a necessity good or a necessary good is a type of normal good. Necessity goods are product(s) and services that consumers will buy regardless of the changes in their income levels, therefore making these products less sensitive to income change. [ 1 ]
Treating logical truths, analytic truths, and necessary truths as equivalent, logical truths can be contrasted with facts (which can also be called contingent claims or synthetic claims). Contingent truths are true in this world, but could have turned out otherwise (in other words, they are false in at least one possible world).
Basic needs such as air, water, food and protection from environmental dangers are necessary for an organism to live. In addition to basic needs, humans also have needs of a social or societal nature such as the human need for purpose, to socialize, to belong to a family or community or other group.