EARLY WORDS FOR SUBSTANCES

The bulk of a child's earliest words are concrete nouns, including names of individuals, names of concrete kinds, and some names for stuffs (“milk,” “juice”). These are acquired in a rush by the dozens between about one and one half and two years old: “this vocabulary spurt is often called the naming explosion to reflect the large preponderance of nouns that are learned” (Markman 1991, p. 81). Adjectives come later and more slowly, and abstract nouns later still. This suggests that the ability to distinguish concrete individuals in thought and the ability to distinguish concrete kinds and stuffs may have something in common, and that concepts of properties and of other abstract objects may not be required for these tasks. There is much independent evidence that children come to appreciate separable dimensions, such as color, shape, and size, only after a considerable period in which “holistic similarities” dominate their attention (see Keil 1989, for discussion). Thus, concepts of properties again appear as less fundamental than those expressed with simple concrete nouns.

We can interpret this data as suggesting that concepts of substances are the easiest for a child to obtain, and more surprising, that the ontological distinction among individuals, real kinds, and stuffs does not produce a difference in ease of early learning. I have proposed that, despite their obvious ontological differences, individuals, real kinds, and stuffs have something important in common that bears directly on what it is to have concepts of them.