Natural Kind Categories Research Articles

Teleological Essentialism: Generalized.

Natural/social kind essentialism is the view that natural kind categories, both living and non-living natural kinds, as well as social kinds (e.g., race, gender), are essentialized. On this view, artifactual kinds are not essentialized. Our view-teleological essentialism-is that a broad range of categories are essentialized in terms of teleology, including artifacts. Utilizing the same kinds of experiments typically used to provide evidence of essentialist thinking-involving superficial change (study 1), transformation of insides (study 2), and inferences about offspring (study 3)-we find support for the view that a broad range of categories-living natural kinds, non-living natural kinds, and artifactual kinds-are essentialized in terms of teleology. Study 4 tests a unique prediction of teleological essentialism and also provides evidence that people make inferences about purposes which in turn guide categorization judgments.

Water Is and Is Not H2O

The Twin Earth thought experiment invites us to consider a liquid that has all of the superficial properties associated with water (clear, potable, etc.) but has entirely different deeper causal properties (composed of “XYZ” rather than of H2O). Although this thought experiment was originally introduced to illuminate questions in the theory of reference, it has also played a crucial role in empirically informed debates within the philosophy of psychology about people’s ordinary natural kind concepts. Those debates have sought to accommodate an apparent fact about ordinary people’s judgments: Intuitively, the Twin Earth liquid is not water. We present results from four experiments showing that people do not, in fact, have this intuition. Instead, people tend to have the intuition that there is a sense in which the liquid is not water but also a sense in which it is water. We explore the implications of this finding for debates about theories of natural kind concepts, arguing that it supports views positing two distinct criteria for membership in natural kind categories – one based on deeper causal properties, the other based on superficial, observable properties.

Preschool Ontology: The Role of Beliefs About Category Boundaries in Early Categorization

These studies examined the role of ontological beliefs about category boundaries in early categorization. Study 1 found that preschool-age children (N = 48, aged 3–4 years old) have domain-specific beliefs about the meaning of category boundaries; children judged the boundaries of natural kind categories (animal species, human gender) as discrete and strict, but they judged the boundaries of other categories (artifact categories, human race) as more flexible. Study 2 demonstrated that these domain-specific ontological intuitions guide children's learning of new categories; children (N = 28, 3-year-olds) assumed that the boundaries of novel animal categories would be narrower and more strictly defined than novel artifact categories. These data demonstrate that abstract beliefs about the meaning of category boundaries shape early conceptual development.

Artifacts and Essentialism

Psychological essentialism is an intuitive folk belief positing that certain categories have a non-obvious inner "essence" that gives rise to observable features. Although this belief most commonly characterizes natural kind categories, I argue that psychological essentialism can also be extended in important ways to artifact concepts. Specifically, concepts of individual artifacts include the non-obvious feature of object history, which is evident when making judgments regarding authenticity and ownership. Classic examples include famous works of art (e.g., the Mona Lisa is authentic because of its provenance), but ordinary artifacts likewise receive value from their history (e.g., a worn and tattered blanket may have special value if it was one's childhood possession). Moreover, in some cases, object history may be thought to have causal effects on individual artifacts, much as an animal essence has causal effects. I review empirical support for these claims and consider the implications for both artifact concepts and essentialism. This perspective suggests that artifact concepts cannot be contained in a theoretical framework that focuses exclusively on similarity or even function. Furthermore, although there are significant differences between essentialism of natural kinds and essentialism of artifact individuals, the commonalities suggest that psychological essentialism may not derive from folk biology but instead may reflect more domain-general perspectives on the world.

Stages of category learning in monkeys (Macaca mulatta) and humans (Homo sapiens).

Smith and Minda (1998) and Blair and Homa (2001) studied the time course of category learning in humans. They distinguished an early, abstraction-based stage of category learning from a later stage that incorporated a capacity for categorizing exceptional category members. The present authors asked whether similar processing stages characterize the category learning of nonhuman primates. Humans (Homo sapiens) and monkeys (Macaca mulatta) participated in category-learning tasks that extended Blair and Homa's paradigm comparatively. Early in learning, both species improved on typical items more than on exception items, indicating an initial mastery of the categories' general structure. Later in learning, both species selectively improved their exception-item performance, indicating exception-item resolution or exemplar memorization. An initial stage of abstraction-based category learning may characterize categorization across a substantial range of the order Primates. This default strategy may have an adaptive resonance with the family resemblance organization of many natural-kind categories.

Essentialist to some degree: beliefs about the structure of natural kind categories.

Previous research has provided conflicting evidence regarding the hypothesis that people are essentialists. Much of the evidence in favor of essentialism is based on demonstrating that categories are thought to have absolute membership. Although the hypothesis is often framed as an absolute claim about all categories of a certain type (e.g., natural kinds), it has generally been tested by making relative comparisons with a select sample. The present study assesses judgments of absolute structure across a range of categories. A further condition for essentialism is that the criteria for category identity be seen as objective rather than conventional. The results of three experiments based on these considerations do not provide support for essentialist claims. Few categories were judged to have essentialist structure, in terms of either absolute membership or objective criteria. Results are discussed in light of an alternative to the essentialist hypothesis that emphasizes a pragmatic view of categories.

Counterfactual reasoning in causal judgments: Implications for marketing

This article describes recent research on counterfactual reasoning in causal judgment and details implications for future research on consumer and managerial decisions. Two types of counterfactual reasoning may be employed in causal judgment, one of which involves outcome contrasts, and is used to generate possible causal explanations, and the other of which involves antecedent contrasts and is used to test candidate explanations. Prior research on outcome contrasts indicates that people compare instances in which the event occurred to instances in which the event did not occur and base their causal explanations on distinctive features between these two types of occurrences. Explanations may therefore vary as a function of the instances chosen for comparison. Prior research findings suggest that consumers and managers may choose different comparison instances depending on their perspective, culture, and perceived norms. Prior research on antecedent contrasts indicates that people test possible explanations for an event by considering instances in which the candidate factor was absent and asking whether the event would have occurred anyway. Findings suggest, however, that consideration of antecedent contrasts may depend on the type of category on which the explanation is based, with less emphasis on antecedent contrasts for explanations based on categories of objects found in nature (natural kind categories) compared to categories of objects made by humans (artifactual categories). This article proposes the hypothesis that people may perceive some brands and product categories as more like natural kinds than artifactual categories and so may be less likely to evaluate causal explanations involving these brands or products with counterfactual processes. © 2000 John Wiley & Sons, Inc.

A Shift in the Development of Natural-Kind Categories

Natural kinds are categories whose superficial distinguishing characteristics are tied together or explained by deeper causal mechanisms. Treating a category as a natural-kind category requires giving priority to more fundamental properties when deciding membership and recognizing a ‘promissory note’ for a deeper explanation, even if none is currently known. Although young children can form and use categories that happen to be natural-kind categories, they cannot treat them as such until after age 4.I describe a number of related shifts – in inferences about hierarchically-related classes, in causal reasoning, and in the child’s understanding of mind – and propose an explanation of all of these shifts as transitions from the first to the second interactive knowing level. I then consider the ability of some other developmental frameworks to give a coherent account of such changes.

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.

Young Children's Inductions from Natural Kinds: The Role of Categories and Appearances

Recent analyses of natural kind terms (e.g., dog, gold) suggest that people expect members of a kind to share unforeseen properties. The present study investigated the development of this expectation by studying children's inductive inferences. On each of a series of problems, 3- and 4-year-old children were taught a new fact about an object and then were asked whether it would generalize to: an object that looked like the original, that had the same label as the original, that looked like the original and had the same label, or that differed from the original in both respects. The results indicate that 3- and 4-year-olds drew more inferences based on category membership than on perceptual appearances, when both were available. Furthermore, children often based their inferences on category membership even when no label was provided. Thus even 3-year-olds assumed that natural kind categories include more than superficial features.

Categories and induction in young children

One of the primary functions of natural kind terms (e.g., tiger, gold) is to support inductive inferences. People expect members of such categories to share important, unforeseen properties, such as internal organs and genetic structure. Moreover, inductions can be made without perceptual support: even when an object does not look much like other members of its category, and even when a property is unobservable. The present work addresses how expectations about natural kinds originate. Young children, with their usual reliance on perceptual appearances and only rudimentary scientific knowledge, might not induce new information within natural kind categories. To test this possibility, category membership was pitted against perceptual similarity in an induction task. For example, children had to decide whether a shark is more likely to breathe as a tropical fish does because both are fish, or as a dolphin does because they look alike. By at least age 4, children can use categories to support inductive inferences even when category membership conflicts with appearances. Moreover, these young children have partially separated out properties that support induction within a category (e.g., means of breathing) from those that are in fact determined by perceptual appearances (such as weight). Since we examined only natural kind categories, we do not know to what extent children have differentiated natural kinds from other sorts of categories. Children may start out assuming that categories named by language have the structure of natural kinds and with development refine these expectations.