 This conclusion may be bewildering to non-linguists as well as non-Essentialists. It is at odds with what a broad range of philosophers have tacitly assumed or explicitly claimed about language or languages: ‘[A language] is a practice in which people engage…it is constituted by rules which it is part of social custom to follow’ (Dummett 1986: 473–473); ‘Language is a set of rules existing at the level of common knowledge’ and these rules are ‘norms which govern intentional social behavior’ (Itkonen 1978: 122), and so on. Generally speaking, those philosophers influenced by Wittgenstein also take the view that a language is a social-historical entity. But the opposite view has become a part of the conceptual underpinning of linguistics for many Essentialists.