 At least some Emergentist linguists, and perhaps some Externalists, would be content to say that languages are collections of social conventions, publicly shared, and some philosophers would agree (see Millikan 2003, for example, and Chomsky 2003 for a reply). Lewis (1969) explicitly defends the view that language can be understood in terms of public communications, functioning to solve coordination problems within a group (although he acknowledges that the coordination could be between different temporal stages of one individual, so language use by an isolated person is also intelligible; see the appendix “Lewis’s Theory of Languages as Conventions” in the entry on  idiolects,  for further discussion of Lewis). What Chomsky calls E-languages, then, would be perfectly amenable to linguistic or philosophical study. Santana (2016) makes a similar argument in terms of scientific idealization. He argues that since all sciences idealize their targets, Chomsky needs to do more to show why idealizations concerning E-languages are illicit (see also Stainton 2014).