Natural Kinds
Natural kinds are the categories that scientific classification aims to track, supporting induction and explanation.
Definition
A natural kind is a grouping of things that reflects the structure of the world rather than mere human convention, such that membership supports inductive inference and figures in laws and explanations.
Scope
This topic covers essentialist accounts of natural kinds, the causal theory of reference for kind terms, the homeostatic property cluster account, and debates over whether biological species and other special-science categories are genuine natural kinds.
Core questions
- Do natural kinds have essences, or are they property clusters?
- How do natural-kind terms refer to their kinds?
- Are biological species natural kinds?
- What distinguishes natural kinds from arbitrary classifications?
Key concepts
- essence
- microstructure
- causal theory of reference
- homeostatic property cluster
- inductive support
- species problem
Key theories
- Essentialism about kinds
- Putnam and Kripke argue that natural kinds such as water and gold have hidden microstructural essences (e.g. H2O) that fix kind membership.
- Homeostatic property cluster theory
- Boyd analyses many natural kinds, especially biological ones, as clusters of properties held together by underlying homeostatic mechanisms rather than strict essences.
History
Putnam and Kripke revived essentialism about kinds in the 1970s with the causal theory of reference and the microstructural conception of kinds like water. Boyd's 1991 homeostatic property cluster account offered a less rigid alternative suited to biology, and debates over the species problem and promiscuous realism continue.
Debates
- Essences versus property clusters
- Microstructural essentialism fits chemical kinds but strains in biology, where Boyd's homeostatic property clusters and Dupré's pluralism argue that messy, overlapping kinds are nonetheless real.
Key figures
- Hilary Putnam
- Saul Kripke
- Richard Boyd
- John Dupré
Related topics
Seminal works
- putnam1975
- kripke1980
- boyd1991
Frequently asked questions
- Why are biological species controversial as natural kinds?
- Unlike chemical elements, species lack a sharp microstructural essence: members vary, boundaries shift through evolution, and many philosophers treat species as individuals or as homeostatic property clusters rather than as classical natural kinds with necessary and sufficient membership conditions.