 HCF leave open exactly what the FLN includes in addition to recursion. It is not ruled out that the FLN incorporates substantive universals as well as the formal property of “recursion”. But whatever “recursion” is in this context, it is apparently not domain-specific in the sense of earlier discussions by generative Essentialists, because it is not unique to human natural language or defined over specifically linguistic inputs and outputs: it is the basis for humans’ grasp of the formal and arguably non-natural language of arithmetic (counting, and the successor function), and perhaps also navigation and social relations. It might be more appropriate to say that HCF identify recursion as a cognitive universal, not a linguistic one. And in that case it is difficult to see how the so-called ‘language faculty’ deserves that name: it is more like a faculty for cognition and communication.