Evaluating a Definition

Evaluating a definition means first identifying what kind of definition it is, then testing it for intruders it wrongly admits, exiles it wrongly excludes, circularity, and emotive wording doing argumentative work.

Grade three. First: a chair is a piece of furniture with four legs. Hunt for intruders — a table is furniture with four legs, so the definition admits what it should exclude. Too broad. Hunt for exiles — a swivel chair rests on one pedestal, so the definition excludes what it should admit. Too narrow as well, and a definition can fail both ways at once. Second: taxation is the confiscation of a citizen's earnings. The word confiscation delivers a verdict, so the definition settles a political question by wording rather than by argument. Third: a prime number is an integer greater than one whose only positive divisors are one and itself. No intruders, no exiles, no circle, no loaded terms. It passes.