Cimpian & Salomon (C&S) propose that an inherence heuristic – people's tendency to explain statistical regularities in the environment by attributing these patterns to inherent factors – is a necessary precursor to psychological essentialism. The crux of this commentary is that inherence is not a separate construct from psychological essentialism; many of the phenomena the authors explain via the inherence heuristic can be explained by psychological essentialism (for system justification, see Keller Reference Keller2005; for nominal realism, see Diesendruck & Haber Reference Diesendruck and Haber2009 and Gelman & Diesendruck Reference Gelman, Diesendruck, Scholnick, Nelson, Gelman and Miller1999). Psychological essentialism also has greater explanatory power than the inherence heuristic alone (for a similar critique of Strevens' K-laws, see Ahn et al. Reference Ahn, Kalish, Gelman, Medin, Luhmann, Atran, Coley and Shafto2001). I discuss evidence that, rather than being a precursor to essentialism, the perception of inherence belongs to a subset of essentialist beliefs. Indeed, inherence is highly correlated with essentialist beliefs (rs up to .74) across a number of studies (e.g., Bastian & Haslam Reference Bastian and Haslam2007; Haslam et al. Reference Haslam, Rothschild and Ernst2000) and is sensitive to manipulations of related essentialist beliefs (Haslam & Ernst Reference Haslam and Ernst2002). Finally, I highlight how psychological essentialism can account for violations of category-based expectations.

Psychological essentialism is the belief that category members share a deep, underlying essence that is responsible for their internal and external attributes, as well as membership in the category. This belief can exist without evidence or even knowledge as to the nature of this essence (i.e., there can be an “essence placeholder” [Medin & Ortony Reference Medin, Ortony, Vosniadou and Ortony1989]). Based on theory and empirical evidence, four core beliefs are related to psychological essentialism: naturalness/biological etiology, immutability, informativeness, and discreteness (e.g., Bastian & Haslam Reference Bastian and Haslam2006; Reference Bastian and Haslam2008). The belief in naturalness/biological etiology is the idea that category membership is based in a biological reality (e.g., chromosomes determine gender). The belief in immutability is the idea that category membership is unchangeable; you cannot change your category membership (e.g., you cannot change genders). The belief in informativeness is the idea that categories are very high in inductive potential, such that membership in a category provides considerable information (e.g., knowing someone's gender is highly informative of who they are). Finally, discreteness is the belief that there are clear separations or distinctions between members of different categories (e.g., there is a clear dividing line between men and women). Earlier theorizing on psychological essentialism suggested that a number of additional beliefs might underlie essentialism (e.g., Haslam et al. Reference Haslam, Rothschild and Ernst2000), but consequent empirical research demonstrated that such beliefs (including inherence) either lacked predictive power or were subsumed by the four core beliefs.

Inherence may be more or less relevant to the inference of an essence depending on the domain or context. Consider the example of pink and blue clothing, as discussed by C&S. Pink and blue (although particularly pink) are colors that are highly diagnostic for gender (Ben-Zeev & Dennehy Reference Ben-Zeev and Dennehy2014). An inherence judgment could lead to inferring an essence, such that if we observe a statistical regularity that more girls wear pink and more boys wear blue, we might conclude that there is something inherently different about girls and boys that relates to their color preferences, and that this difference is essential (“little girls are made of sugar and spice…” and therefore must like pink). However, I propose that, in the case of gender and clothing color, the inference of an essence would more likely follow from discreteness and informativeness judgments (with inherence judgments arising as a consequence of perceiving an essence). Say we observe a distinct pattern among boys and girls on the playground that boys predominantly wear blue and girls predominantly wear pink. This could lead us to judge that children in pink versus blue belong to discrete and informative groups. Discreteness and informativeness are both aspects of psychological essentialism (e.g., Haslam et al. Reference Haslam, Rothschild and Ernst2000; Haslam & Levy Reference Haslam and Levy2006); simply observing or attributing discrete or informative features to groups may be sufficient information for us to assume that something must be causing boys to wear blue and girls to wear pink. C&S assert that we would ask the question “Which inherent features explain this pattern?” and that we would apply an inherence judgment to the color pink, concluding that it is inherently more delicate and is therefore more suited to girls. However, I propose that this step is unnecessary. Once we have observed a pattern consistent with essentialist reasoning, we can apply an essence placeholder and assume that there is an essence underlying the pattern we observe.

Psychological essentialism and inferences of essentiality can also account for violations of statistical regularities in a way that inherence-based reasoning alone does not. Of relevance, Rehder and Burnett (Reference Rehder and Burnett2005) have proposed an underlying mechanism model, which posits that people have a bias toward perceiving underlying mechanisms that cause category-based features (e.g., testosterone could be seen as the underlying mechanism causing facial hair in men). Similar to Medin and Ortony's (Reference Medin, Ortony, Vosniadou and Ortony1989) concept of the “essence placeholder,” people do not require concrete information about the underlying mechanism to assume its existence; it is something that is simply inferred. The underlying mechanism model is highly complementary to psychological essentialism because the mechanism may be the (known or unknown) means by which essences cause observed features. This mechanism can function either well or poorly, explaining within-category variation (e.g., not all girls wear pink) beyond the between-category variation (e.g., boys wear blue and girls wear pink) accounted for by the presence or absence of an essence.

To apply Rehder and Burnett's (Reference Rehder and Burnett2005) theorizing and findings to human social categories, consider the case of a boy wearing pink. Psychological essentialism in conjunction with the underlying mechanism model can account for violations of category-based expectancies. In the case of gender and clothing color, a boy dressed in pink might be perceived as having a less well-functioning mechanism that is responsible for the feature of “not-pink” given his essence of being male. A judgment of a poorly functioning mechanism could account for him still belonging to the category of male while exhibiting a feature (pink clothing) not typically associated with maleness.