Abstract

Experiments have led some philosophers to conclude that the reference determination of natural kind terms is neither simply descriptive nor simply causal-historical. Various theories have been aired to account for this, including ambiguity, hybrid, and different-idiolects theories. Devitt and Porter (2021) hypothesized that some terms are covered by one theory, some another, with a place for all the proposed theories. The present paper tests hypotheses that the term ‘Rio de Janeiro Myrtle’ is simply causal-historical but the term ‘rice’ is hybrid. For, whereas the former term is of scientific but little practical interest, the latter is not: rice is a significant part of the human diet. So, we predicted there would be two factors to the reference determination of ‘rice’: a superficial-descriptive one and a deep-causal one. Our experiments confirmed these hypotheses using the methods of elicited production and truth value judgments. We take our results to support the hybrid Theory of ‘rice’ rather than the ambiguity or different-idiolects theory. We were not testing ‘myrtle’ but, surprisingly, our results implied that ‘myrtle’ was partly descriptive and so like ‘rice’ but not ‘Rio de Janeiro Myrtle’. A follow-up experiment confirmed these puzzling results. More investigation is needed.