Full Idea
Putnam takes causes to be the essence of disease kinds, and they are distinct from the diseases they cause, both in identity and in proper parthood. These are relational properties, so Putnam gives examples of natural kinds with relational essences.
Gist of Idea
If causes are the essence of diseases, then disease is an example of a relational essence
Source
report of Hilary Putnam (The Meaning of 'Meaning' [1975]) by Neil E. Williams - Putnam's Traditional Neo-Essentialism §4
Book Reference
-: 'The Philosophical Quarterly' [-], p.16
A Reaction
This seems to be a nice point, since scientific essentialism invariable takes itself to be pursuing instrinsic properties when it unravels the essences of natural kinds. Probably the best response is the Putnam has got muddled.