Essentially Contested Concept

In a paper delivered to the Aristotelian Society on 12 March 1956, Walter Bryce Gallie (1912–1998) introduced the term essentially contested concept to facilitate an understanding of the different applications or interpretations of the sorts of abstract, qualitative, and evaluative notions — such as "art" and "social justice" — used in the domains of aesthetics, political philosophy, philosophy of history, and philosophy of religion.

Garver (1978) describes their use as follows:

The term essentially contested concepts gives a name to a problematic situation that many people recognize: that in certain kinds of talk there is a variety of meanings employed for key terms in an argument, and there is a feeling that dogmatism (“My answer is right and all others are wrong”), skepticism (“All answers are equally true (or false); everyone has a right to his own truth”), and eclecticism (“Each meaning gives a partial view so the more meanings the better”) are none of them the appropriate attitude towards that variety of meanings.

Essentially contested concepts involve widespread agreement on a concept (e.g., "fairness"), but not on the best realization thereof.

They are "concepts the proper use of which inevitably involves endless disputes about their proper uses on the part of their users", and these disputes "cannot be settled by appeal to empirical evidence, linguistic usage, or the canons of logic alone".