Are there “social kinds” the way there are “natural kinds”? Are social sciences likely to hit upon “essences” the way natural sciences (seem to) do? Or are all social phenomena purely theoretical constructs? Questions about whether there are natural kinds, what exactly they are and which kinds of phenomena they cover have been the object of heated epistemological and metaphysical debates (e.g. Schwarz 1983). We think the issues can be clarified within the limits of the philosophy of language: by looking into what ranges of general terms are perceived by speakers as rigid designators of natural kinds. The first step to take is to ground the various kinds of semantic externalism in distinct brands of semantic deference. This we define as speakers’ being disposed to use words in line with the norms of their linguistic community and as consenting to being corrected when it is manifest that their use and understanding of a word does not match common practice (and caused the falsity of some of their previous statements, which they are retrospectively willing to acknowledge). When those dispositions are present, speakers defer semantically to something beyond themselves. Our focus is on spotting the words for which speakers would defer not (just) to the current usage of the word in the linguistic community, nor to the current experts of the field to which the word pertains, but ultimately to the very nature of the referent of the term. When speakers’ deference conforms to that pattern, we argue, that is evidence that indexical externalism (à la Kripke or Putnam) provides the right metasemantic account of how the meaning of the word is determined; the word is treated like a natural-kind term. But how can patterns of deference be measured? In an ongoing survey, which shows a kinship with work by Braisby et al. (1996), Jylkkä et al. (2009), and Genone & Lombrozo (2012), we confront participants with conditions that may prompt them to revise certain classificatory statements, e.g. An emu is a bird; Touching a stranger’s breast without their consent is rape. Each condition makes salient one of the targets we have identified for deference: the community usage, the experts, the ‘world as it is’. In the condition that seeks to tap into the latter kind of deference, participants are presented with a scenario in which future scientific discoveries result in excluding from the extension of a term certain members currently thought to fall under that extension. Our reasoning is that, if participants significantly modify their statements in the light of that scenario, they can be taken to ‘defer’ to the nature of the referent, thus vindicating indexical externalism. We test if words not normally assumed to be naturalkind terms, including terms for social phenomena, exhibit patterns of deference similar to those for natural-kind terms. If so, speakers have something like realist intuitions with respect to words whose meaning is usually taken to be purely conventional or polemical, and there’s therefore a case for an extension of indexical externalism beyond its usual boundaries. Braisby, N., Franks, B. & Hampton, J. 1996. Essentialism, word use, and concepts. Cognition 59, 247-74./Genone, J. & Lombrozo, T. 2012. Concept possession, experimental semantics, and hybrid theories of reference. Philosophical Psychology 25, 717-742./Häggqvist, S. & Wikforss, Å. 2015. Experimental semantics: the case of natural kind terms, in J. Haukioja (ed), Experimental Philosophy of Language, London, Bloomsbury./Jylkkä, J., Railo, H. & Haukioja, J. 2009. Psychological essentialism and semantic externalism: Evidence for externalism in lay speakers’ language use. Philosophical Psychology 22, 37-60./Mallon, R., Machery, E., Nichols, S. & Stich, S. 2009. Against arguments from reference, Philosophy and Phenomenological Research 79, 332-356./ Marconi, D. 1997. Language, Speech, and Communication. Lexical Competence. Cambridge (Mass.): MIT Press./Moravcsik, J. 2016. Meaning, Creativity, and the Partial Inscrutability of the Human Mind, 2nd ed. Stanford: CSLI./Schroeter, L. & Schroeter, F. 2014. Normative concepts: a connectedness model. Philosophers’ Imprint 14, 1-26./Schwarz, S. 1983. Reply to Kornblith and Nelson. The Southern Journal of Philosophy 21, 475-481./Wikforss, Å. 2010. Are natural kind terms special?, in H. Beebee and N. Sabbarton-Leary (eds), The Semantics and Metaphysics of Natural Kinds, New York, Routledge, 64-83.