 Extensional. First, there is an attempt to impugn the extensional notion of a language that is found in two radically different strands of Externalist work. Some Externalist investigations are grounded in the details of attested utterances (as collected in corpora), external to human minds. Others, with mathematical or computational interests, sometimes idealize languages as extensionally definable objects (typically infinite sets of strings) with a certain structure, independently of whatever device might be employed to characterize them. A set of strings of words either is or is not regular (finite-state), either is or is not recursive (decidable), etc., independently of forms of grammar statement. Chomsky (1986) basically dismissed both corpus-based work and mathematical linguistics simply on the grounds that they employ an extensional conception of language that is, a conception that removes the object of study from having an essential connection with the mental.