Thus, Gallie argued:
So long as contestant users of any essentially contested concept believe, however deludedly, that their own use of it is the only one that can command honest and informed approval, they are likely to persist in the hope that they will ultimately persuade and convert all their opponents by logical means. But once [we] let the truth out of the bag - i.e., the essential contestedness of the concept in question - then this harmless if deluded hope may well be replaced by a ruthless decision to cut the cackle, to damn the heretics and to exterminate the unwanted. (Gallie, 1956a, pp.193-194)
==========
There should be a distinction between (a) disputed concepts and (b) different senses of words.
As I've mentioned in other posts, there are more things in the world than there are in any language, and it follows that the 'same' word _must_ be used in incompatible senses, but that that should _not_ be seen as a matter of dispute. This is obvious enough in the case of metaphors, especially "half-alive" metaphors. "He's a donkey." Here "donkey" is very nearly a dead metaphor, having the simple _literal_ sense of stubbornly stupid. But it also carries some of its sense of a particular mammal. No one would, however, argue over what the word _should_ mean.
But take what is sometimes a "hotly" or even "essentially" disputed word and/or concept: ideology.
This word (nly a couple centuries old) has a number of quite different, even contradictory, senses. I think it wrong, even obscurantist, to argue about _which_ of those senses is the "true" meaning or "true concept." They are all simply different, and users of the word must allow for that; where there might be confusion, they have to define their use of the term and readers should _accept_ that definition in that context, not argue about it. In one sense of the word it is roughly synonymous with "theory." In another sense, it is definitely _not_ synonymous with theory but in contrast with that word. And no one should quibble over which sense is the _true_ sense. The word may denote a system of explicit beliefs, as when we speak of "Marxism-Leninism" or "Trotskyism" as ideological positions. I prefer myself to _use_ the word as roughly equivalent to "common sense," to the spontaneous assumptions within which various specific structures of belief can exist. For example, two persons may both think "race" is real: One argues that members of a given race have a lower IQ than members of some other race; the other person may claim there is no difference, and they may argue hotly, and behave quite differently. But I (following Barbara Jeanne Field) would see _race_ itself as an ideological term, not the name of anything real. Hence both are racists because both except the reality of race.
I see possibilities for all sorts of debate and confusion in the preceding paragraph; it is crudely written. But I won't accept as meaningful any argument that the _word_ should mean only one of the different concepts mixed up above. It can legitimately be applied to any of the concepts, just as "dog" can be a noun referring to an animal or a verb referring to a practice.
Carrol