Full Idea
The animating principle behind the material and discursive practices of science is the thesis that nature exemplifies multiple hierarchies of natural kinds.
Gist of Idea
Science rests on the principle that nature is a hierarchy of natural kinds
Source
Rom Harré (Laws of Nature [1993], 5)
Book Reference
Harré,Rom: 'Laws of Nature' [Duckworth 1993], p.102
A Reaction
I agree. I take it to be a brute fact that there seem to be lots of stable natural kinds, which are worth investigating as long as they stay stable. If they are unstable, there needs to be something stable to measure that by - or we give up.