Cimpian & Salomon (C&S) argue that a reliance on inherent explanations may be a precursor to psychological essentialism and especially in the case of living kinds. They suggest that essentialist beliefs arise through a refinement process where ideas about general causal forces (such as internal energy, commonly referred to as vitalism [Inagaki & Hatano Reference Inagaki and Hatano2004]) translate the inchoate early output of the inherence heuristic into a kind specific essence that is responsible for static as well as dynamic features.

Inherence is an important component of essentialist beliefs (e.g., Bastian & Haslam Reference Bastian and Haslam2007) and is most often characterized by a belief in the biological basis of natural kinds (Bastian & Haslam Reference Bastian and Haslam2008). However, a belief in underlying biological characteristics that cause tigers to look and behave in similar ways, or that make pine trees different from willow trees, is not the same as a belief in a generalized causal force (internal energy) that makes tigers move or trees grow. Children do not refer to stable inherent features when they posit the existence of internal energy. Rather, they refer to causal forces that may even be transferable or exchangeable between entities themselves. For example, energy transmission may be used to explain why one ball moves when hit by another ball (Morris et al. Reference Morris, Taplin and Gelman2000). Within the biological domain, conceptions of energy may be more akin to a general life force as opposed to something that defines the shared attributes of category members.

How do ideas about energy, which are not specific to kinds but explain growth or movement in general, translate the output of the inherence heuristic into full-blown essentialist accounts? According to C&S, the output of the inherence heuristic is a focus on “stable, enduring characteristics of the entities in question” (sect. 2.2.1, para. 1) Essentialist beliefs share this focus on stable or fixed features that distinguish different kinds. Ideas about internal energy, however, do not distinguish between kinds and are not linked to fixed characteristics, making their role in this process somewhat unclear. As C&S note, “the essentialist belief constructed via this refinement process must transcend children's original ideas about internal energy” (sect. 4.3, para. 5).

This disjuncture between a belief in vital energy and a tendency to attribute fixed essences to kinds is not only apparent in early childhood but also evident within adult thinking. Beliefs in general vital forces, energies, power, or spirits are evident within many traditional belief systems (Frazer Reference Frazer and Gaster1890/1959; Mauss Reference Mauss, Brain and Norton1902/1972; Tylor Reference Tylor1871/1974) and in adult superstitious thinking (Lindeman & Saher Reference Lindeman and Saher2007; Nemeroff & Rozin Reference Nemeroff and Rozin1994), and feature in theories such as astrology, feng shui, or homeopathy (Fisher Reference Fisher2002). Perhaps most striking is the observation that causal explanations regarding agent intentionality rely on forms of vitalistic reasoning (Cashmore Reference Cashmore2010). Agent intentionality, at its core, relies on a belief in free will – that some internal causal property not determined by biological processes (e.g., the soul) is responsible for individual action.

Just like the concept of internal energy, the concept of souls is not clearly attached to stable or fixed features. Souls can be tarnished, cleansed, converted, corrupted, or lost. One can sell his or her soul to the devil or engage in reprehensible behaviors that contaminate the soul. Luckily, however, souls can also be rehabilitated and purified (Bastian et al. Reference Bastian, Jetten and Fasoli2011; Zhong & Liljenquist Reference Zhong and Liljenquist2006). Souls may also be easily influenced by external factors. Consider the reasoning of televangelist Pat Robertson when he said that the earthquake-ravaged Haiti has been “cursed” by a “pact to the devil” (Shea Reference Shea2010). This causal explanation draws on both external events (a historical pack with an external entity) and internal qualities (the souls of Haitians). Souls provide excellent causal explanations, but like energy or other vital forces, they are not linked to stable or fixed features and they do not serve to distinguish between different kinds.

Of course, it is clear that C&S did not set out to explain a belief in souls or free will. These examples do, however, raise the question of how the inherence heuristic may be related to vitalism (as opposed to essentialism). Recent work has identified that people rely on vitalistic beliefs within the moral domain (Bastian et al. Reference Bastian, Bain, Buhrmester, Gómez, Vázquez, Knight and Swann2013). Specifically, some people endorse a belief in forces of good and evil, implying that they see these forces as real and agentic. Such beliefs appear to have a range of implications for social cognition, shaping how people understand ideological (as opposed to strictly biological) differences among people. Moreover, these beliefs are not attached to entities, but capture how people think about good and evil in general. This demonstrates that vitalistic beliefs appear to be largely distinct from essentialist beliefs – a distinction that not only makes it hard to understand how vitalistic beliefs enable the development of essentialism from the output of the inherence heuristic, but also raises the question of how the inherence heuristic may apply in these cases. Can the inherence heuristic explain a reliance on vitalistic reasoning in both children and adults? Put differently, can the inherence heuristic explain the many ways in which people seek to make intuitive sense of the world by relying on causal properties that are not themselves fixed characteristics linked to kinds?

One would assume that the same mechanism underlying the inherence heuristic – the mental shotgun – would be responsible for promoting vitalistic reasoning in more complex domains, such as human morality. For example, the mental shot gun would likely support character-based explanations for criminal behavior (a bad soul) as opposed to a range of behavior determining developmental and environmental factors. This is particularly apparent in the case of more heinous crimes, where explanations based on external factors seem less fitting: we are more likely to see Hitler as evil than as a victim of hard times.

The inherence heuristic serves to integrate a number of well-known, influential theories. Examining how the heuristic may extend to intuitive explanations based on fluid and shifting internal properties (vitalistic beliefs) may broaden its influence further still.