Full Idea
Natural necessity involves the concept of generative mechanisms and powerful particulars, and these in turn can be the basis of a useful notion of a natural kind.
Gist of Idea
We can base the idea of a natural kind on the mechanisms that produce natural necessity
Source
Harré,R./Madden,E.H. (Causal Powers [1975], 7.V)
Book Reference
Harré,R/Madden,E.H.: 'Causal Powers: A Theory of Natural Necessity' [Blackwell 1975], p.134
A Reaction
Not sure about that. Say gold and silver are two kinds that lead to two outcomes. Each is a natural necessity. How do you distinguish them? Only by one being the gold-necessity and the other the silver-necessity. Circular?