Full Idea
In my view, Kripke's promotion of 'natural kinds', coverning chemical substances and animal and plant species, is unfortunate, since these are rather different types of things, and words used for them behave differently.
Gist of Idea
Generalised talk of 'natural kinds' is unfortunate, as they vary too much
Source
Michael Dummett (Could There Be Unicorns? [1983], 2)
Book Reference
Dummett,Michael: 'The Seas of Language' [OUP 1993], p.331
A Reaction
My view is that the only significant difference among natural kinds is their degree of stability in character. Presumably particles, elements and particular molecules are fairly invariant, but living things evolve.