more from Thomas Mautner

Single Idea 6877

[catalogued under 5. Theory of Logic / B. Logical Consequence / 6. Entailment]

Full Idea

Entailment is the modern word saying that p logically follows from q. Its simplest definition is that you cannot have both p and not-q, but this has the problem that if p is impossible it will entail every possible proposition, which seems unacceptable.

Gist of Idea

Entailment is logical requirement; it may be not(p and not-q), but that has problems


Thomas Mautner (Penguin Dictionary of Philosophy [1996], p.169)

Book Reference

Mautner,Thomas: 'Dictionary of Philosophy' [Penguin 1997], p.169

A Reaction

The word 'entail' was introduced by G.E. Moore in 1920, in preference to 'imply'. It seems clear that we need terms for (say) active implication (q must be true if p is true) and passive implication (p must be false if q is false).