["Journal for the Theory of Social Behaviour, Volume 56, Issue 2, June 2026. ", "\nABSTRACT\nProgress and dialogue in cultural analysis are often hindered by analysts' reliance on implicit ontic claims, namely, foundational, unstated assumptions about the expected properties and typical characteristics of cultural kinds, thus precluding proper debate and theoretical progress. This paper develops a systematic four‐part taxonomy of these claims, distinguishing among compositional claims (what culture is made of), locational claims (where cultural kinds exist in the world), property claims (necessary traits such as systematicity) and aetiological claims (their origin or provenance). I argue that explicitly articulating these claims is essential to moving beyond mere methodological disagreements and to building a robust cultural science. I use this framework to critically consider two persistent and problematic tendencies in cultural theory. First, I argue against compositional claims that posit culture as nonmaterial or ‘deal’ stuff, as this commits analysts to a philosophical substance dualism that struggles to explain cultural causation in the physical world. Second, I challenge the use of sharedness as a definitional property of culture, arguing that this focus commits a ‘groupist’ fallacy. Dropping sharedness as a criterion allows analysts to focus instead on the explicit social processes (such as instruction and imitation) that make culture widespread while recognising that cultural novelty fundamentally arises from individual ingenuity and learning.\n"]