Also known as the criterion of identity. The principle associated with a kind of thing, telling when we have two of them and when we have one. Thus to count words it is necessary to know whether we suppose that variations of spelling, or meaning, or etymology, give us two different words, and when they allow us to rest with one word (see also type-token ambiguity). We also need to know when two appearances or stages can rightly be regarded as appearances or stages of just one thing of the kind. A principle of individuation for nations would tell whether a nation survives such things as shift of territory, of government, of origin of inhabitants, of language, and so on. A relaxed attitude is that we solve such cases as we go along, depending on the consequences of the different verdicts, and apparently doing without cast-iron principles. This relaxed attitude was opposed by Quine, at least for languages fit to express proper scientific facts, with the slogan ‘no entity without identity’ (‘Speaking of Objects’, 1958).