Supernatural beliefs,natural kinds,and conceptual structure

This article presents cross-cultural evidence in support of the notion that adults' natural kind concepts are theory based but may be informed by knowledge/belief systems other than the biological. Three groups of subjects from western Nigeria--rural, urban, and elite--participated in the study. Subjects heard stories describing alterations of appearance; that is, one natural kind was made to resemble another in both ritual and nonritual contexts. Subjects then were required to judge the identity of the altered item and to give an explanation for the category judgment. It was predicted that subjects would make more nonpreservation-of-identity category judgments supported by supernatural explanations in the ritual contexts and that subjects' use of supernatural explanations would reflect the extent of their engagement with the supernatural. The first prediction was borne out; the second prediction was only partially supported. Discussion of the results emphasizes the importance of exploring the role of sociocultural factors in conceptual structure.     

Development and natural kinds

While philosophers tend to consider a single type of causal history, biologists distinguish between two kinds of causal history: evolutionary history and developmental history. This essay studies the peculiarity of development as a criterion for the individuation of biological traits and its relation to form, function, and evolution. By focusing on examples involving serial homologies and genetic reprogramming, we argue that morphology (form) and function, even when supplemented with evolutionary history, are sometimes insufficient to individuate traits. Developmental mechanisms bring in a novel aspect to the business of classification—identity of process-type—according to which entities are type-identical across individuals and natural kinds in virtue of the fact that they form and develop through similar processes. These considerations bear important metaphysical implications and have potential applications in several areas of philosophy.     

Extensionality, underdetermination and indeterminacy

I am grateful to Burton Dreben, Warren Goldfarb, Don Gustafson, Jim Higginbotham, Jerrold Katz, Joe Levine, Ted Morris, Nick Pappas, Hilary Putnam, Georges Rey and Bob Richardson for helpful discussions and comments on the issues discussed in this paper. Also I thank an anonymous reviewer for Erkenntnis for helpful comments.     

Disjunction of natural concepts

Two experiments investigated the way in which the rated membership of items in disjunctively defined categories, such as FRUITS OR VEGETABLES and PETS OR FARMYARD ANIMALS, varies as a function of membership in individual constituent categories. Items were rated for category membership and typicality in each category separately, and in their disjunction. The results showed non-Boolean effects of both overextension and underextension of the disjunctions. Typicality in the disjunction was highly predictable from constituent typicality values, using regression equations with negative interaction terms. The results are compared with similar effects for concept conjunctions and are discussed in terms of an intensional model of conceptual combination (Hampton, 1987b, 1988).     

Diseases as natural kinds

In this paper, I focus on life-threatening medical conditions and argue that from the point of view of natural properties, induction(s), and participation in laws, at least some of the ill organisms dealt with in somatic medicine form natural kinds in the same sense in which the kinds in the exact sciences are thought of as natural. By way of comparing two ‘divisions of nature’, viz., a ‘classical’ exact science kind (gold) and a kind of disease (Graves disease), I show that there is no justifiable ‘ontological gap’ between disease kinds and exact sciences kinds. We have instead a difference of degree.     

Metamorphosis: Essence, appearance, and behavior in the categorization of natural kinds

The transformation paradigm (Rips, 1989) was used to contrast causal homeostasis and strict essentialist beliefs about biological kinds. Participants read scenarios describing animals that changed their appearance and behavior through either accidental mutation or developmental maturation and then rated the animals on the basis of similarity, typicality, and category membership both before and after the change. Experiment 1 in the present study replicated the dissociation of typicality and categorization reported by Rips (1989) but also revealed systematic individual differences in categorization. With typicality and membership ratings collected between participants, however, Experiment 2 found no evidence for the dissociation and few essentialist responders. In Experiment 3, excluding information about offspring led most participants to categorize on the basis of appearance and behavior alone. However, with offspring information included and with questioning focused on the change of kind, essentialist categorization was still surprisingly rare. We conclude that strict essentialist categorization in the transformation task is relatively rare and highly task dependent, and that categorization is more commonly based on causal homeostasis.     

Defining features of natural kinds and artifacts

Two experiments investigated the role of three types of features (physical characteristics, functions, and chromosomal/molecular structure) in determining membership in natural kind and artifact categories. In the first, subjects decided if an object X would still be an X if it were different in one type of feature. A significant interaction was found between word type and change type, with the effects of chromosomal/molecular changes significantly greater for natural kinds than for artifacts, and the effects of functional changes significantly greater for artifacts than natural kinds. In the second experiment, subjects judged whether something would be an X if it were unlike instances of X in two of the above types of features, but like instances of X in one. There was again a significant interaction, with the effects of chromosomal/molecular features significantly greater for natural kinds than for artifacts, and the effects of functional changes significantly greater for artifacts than for natural kinds. These results suggest that chromosomal/molecular features define membership in natural kind categories and functional features define membership in artifact categories. The implications of these findings for the meaning of defining features are also discussed.The first experiment was conducted by the first author as part of a senior comprehensive exercise at Carleton College. We thank Kathleen Galotti, Matthew Gish, Neil Lutsky, and an anonymous reviewer for comments on earlier drafts of this article.