 In reply, some incompatibilists subversively suggest that switches do occur on a regular basis (Ludlow 1995b; Butler 1997). In section  1,  we saw that one “Twin Earth” scenario might occur in the actual world: Recall the superficially indiscernible extensions of ‘chicory’ and ‘endive’, which are swapped between British and Standard American English. An American ex-patriot thus could be unwittingly fooled into denoting chicory when speaking or thinking about “endive.” Still, this seems like an atypical case. But to the contrary, the potential for an undetected switch might be as common as the potential for polysemy in the language (Ludlow 1995b). Consider that between different philosophical circles, the term ‘pragmatism’ denotes different yet superficially similar philosophical theses. So thanks to unnoticed switches between subgroups, one might be fooled into saying or believing things about different kinds of pragmatism. Such variation among linguistic subgroups seems entirely commonplace. It is the prevalence of these switches, moreover, that makes them relevant even if no actual switch occurs in a given instance.