Full Idea
A statement which asserts that a substance or thing must manifest certain properties in order to be identified as a thing or substance of that sort can be laid down a priori.
Gist of Idea
What properties a thing must have to be a type of substance can be laid down a priori
Source
Harré,R./Madden,E.H. (Causal Powers [1975], 1.IV)
Book Reference
Harré,R/Madden,E.H.: 'Causal Powers: A Theory of Natural Necessity' [Blackwell 1975], p.17
A Reaction
This observation is encountered in Sidelle, but this is earlier, and seems to be the key to the Twin Earth thing. It is just convention whether we call XYZ water, or whether there are two sorts of jade or one. Science has prestige.