In this paper I will be reviewing literature, mostly from cognitive science, related to the human brain’s processes of categorization

IV.Natural essences in human thought

It could be objected at this point that the above does not really demonstrate that Torguuds process their local ethnic categories in the way they do species categories. What the data show is that one will take on the ethnic ascription of one’s biological father, period. It could be that, to them, an ethnic group is simply a ‘descent’ group, and that the question “what is the child’s ündesten” (ündesten is the Mongolian word used to describe groups at the level of contrast between Mongols and Kazakhs)⁵ is understood simply as “what is the child’s descent group”, as in “which group is he biologically descended from”. Indeed, the root morpheme of ündesten (ündes) means ‘root’. To show that ethnies are processed as natural kinds one must go beyond this and provide evidence that putative essences are attached to the labels. I will provide such evidence, but for it to be appreciated, we must first consider how essentialism influences thought.

A.Psychological essentialism

How important is shared appearance in the construction of categories? Medin & Ortony (1989) note that Goodman (1972) and Watanabe (1969) have given formal proofs that, on the basis of shared predicates, all pairs of entities are equally similar. The reason is that an infinite number of things can be predicated about any entity, and infinity is not a number that can be subjected to relative comparisons such as “A has more predicates in common with B than it does with C.” Thus, they argue that ‘similarity’ should be understood “not in terms of logically possible shared predicates but in the more restricted sense of represented predicates” (Medin & Ortony 1989:182). Certain things seem more similar to each other than to other things, because our brains represent them that way, effectively filtering out many logically possible predicates as immaterial to categorization. “For example, both tennis balls and shoes share the predicate ‘not having ears’, but it is unlikely that this predicate is part of our representation of either tennis balls or shoes” (ibid. p.182). They believe that surface similarity serves as a good heuristic to search for deeper or ‘hidden’ properties, which are the ultimate arbitrators of categorization.

I agree with M&O that our judgments of similarity must be theory-rich, and that “psychological similarity may depend on categorization rather than the other way around” (Rips 1989:22), but I think they may have overemphasized the extent to which such theory is a matter of ‘surface’, ‘visible’ properties vs. ‘deep’ or ‘hidden’ properties. With artifacts, for example, it is their relation to humans that brings an infinite number of possible predicates down to a few relevant ones.⁶ Their example is a case in point; tennis balls get thwacked by rackets in tennis courts, and shoes are worn on feet, and this brings to the fore the relevance of predicates such as “shoes have an opening (for sliding the foot into)”, “tennis balls are brightly colored (to improve their visibility to the players who must thwack them)”, etc. These are not ‘hidden’ properties; we usually have no problem identifying the uses of artifacts because people are using them all the time, and it is their uses which ground our standards of similarity (cf. Gelman 1988). M&O’s surface/depth distinction is better suited to our theories of natural kinds, as they themselves concede:

…psychological similarity is tuned to those superficial properties that are likely to be causally linked to a deeper level. This is particularly likely to be true with respect to natural kinds.—Medin & Ortony (1989:186)

Their theoretical proposal, ‘psychological essentialism’, is the idea that humans believe that natural kinds have constitutive and inalienable hidden ‘essences’. This theory has the advantage of explaining why dissimilar objects can be included in the same category (i.e. when they are believed to share the same ‘hidden’ essence).

None of this commits us to the belief that essences exist. One may certainly argue that, for some natural kinds such as ‘substances’ and ‘elements’, their chemical or atomic constitutions may qualify as a specification of a legitimately real essence; but the Darwinian revolution made it clear that biological natural kinds cannot be characterized as having real essences (Mayr 1964). This is because the nature of genetic variation and the evolutionary process are such that, for any given genetic locus, either (1) there is variation now, or (2) there will be variation at some point in the future, and such variation does not ipso facto force an unusual variant or mutant out of the category which names the population (in fact, typically it does not).⁷ This, however, does not deny that we may think in essentialist terms. ‘Psychological essentialism’, as this proposal has been baptized, is “not the view that things have essences, but rather the view that people’s representations of things might reflect such a belief (erroneous as it may be)” Medin & Ortony (1989:183; original emphases). It is a hypothesis about a ‘naïve ontology of natural kinds’—i.e. about how people think about natural kinds, and not about the ontological status of such things.

B.Essences and development in living kinds

Perhaps the most interesting suggestion in M&O’s ‘psychological essentialism’ is the idea that a natural kind may have an ‘essence placeholder’. In other words, that with regard to a natural kind, we will assume the existence of an essence which makes the thing the thing that it is, even when we don’t have the first clue as to what that essence is. Thus, the essence placeholder may be empty or full, but we in any case always have the placeholder. According to Medin & Ortony (1989:184-185), the essence placeholder

…might be filled with beliefs about what properties are necessary and sufficient for the thing to be what it is. In other cases it might be filled with a more complex, and possibly more inchoate, ‘theory’ of what makes the thing the thing that it is. It might, additionally, contain the belief (or a representation of the belief) that there are people, experts, who really know what makes the thing the thing that it is, or scholars who are trying to figure out exactly what it is. Just as with theories, what the placeholder contains may change, but the placeholder remains.

To me it seems the placeholder either has predicates constituting a set of properties, or is empty. The belief that experts may know the essence is not an idea that is in the placeholder, but rather a belief that something is supposed to go in it, and that other people know what that is; or else that other people at least know when something has the essence (whether or not they can tell you what the essence is). Recall here the ‘fool’s gold’ example, where those of us who don’t know the first thing about chemistry accept that some people know why such a thing is not gold. What is paramount here is not that there be something in the placeholder, but that the existence of the placeholder––the assumption of an essence––implies a particular way of conceptualizing the category. The idea of less-than-full essence placeholders receives support from studies with children, for “Young children have impoverished scientific knowledge, yet firmly believe that [natural kind] category members have more in common than meets the eye” (Gelman & Markman 1986:199).

I think it is more useful to think of essence placeholders as ‘not full’, rather than empty. For whatever content is in our essence placeholder for a particular natural kind, our brains probably always expect that more hidden properties can be learned about it (this assumption about natural kinds has allowed us to develop sciences about them (Schwartz 1978:571-573 note: get this reference form Keil, mapping mind). Natural living kinds, in any case, do seem to come with essence placeholders that are not entirely empty (at least at the generic-species level), as revealed in children´s reasoning about development. Gelman & Wellman (1991) investigated children’s views of development by testing to see if they assume that common membership in a species implies a common, innate, developmental potential.

…a tiger cub has the potential to grow into something large and fierce, even though when born it is small and helpless. To explain developmental changes of this sort, we as adults often appeal to something like an intrinsic category essence that is responsible for how they grow…the belief in an essential nature or a determining but [at an early age] non-manifest predisposition.—Gelman & Wellman (1991:230)

The children were presented with examples of animals (e.g. tiger) that were raised with another kind of animal (e.g. horses) and in complete absence of their own kind. To questions concerning the form and behavior of these animals as adults, children relied more on category than on environment.⁸ For example, they answered that a tiger raised with horses (and never having seen another tiger after the early transfer) would display tiger traits and behaviors as an adult rather than horse traits and behaviors. Children seem aware that the nature of an animal is relatively impervious to the environment of development, and that adult traits and behaviors not present in the earlier stages of ontogeny are the product of the animal’s intrinsic developmental program rather than elicited by, or acquired from, an environment of conspecifics already exhibiting the traits and behaviors in question.

Remember The ugly duckling? Same story: categorical identity for members of a species is stable in the face of varying environments of rearing, and it implies that the adopted animal will develop to display the adult features and behaviors of the species-category from which it is biologically descended.