Full Idea
If empirical predicates are linked in clusters, contraposition of (black, raven) would carry one via such pairs as (shoe, white) into a different empirical cluster, or no cluster at all.
Clarification
A→B so ¬B→¬A is contraposition
Gist of Idea
The items put forward by the contraposition belong within different natural clusters
Source
Harré,R./Madden,E.H. (Causal Powers [1975], 7.I)
Book Reference
Harré,R/Madden,E.H.: 'Causal Powers: A Theory of Natural Necessity' [Blackwell 1975], p.124
A Reaction
This is, of course, addressed to Hempel's Raven Paradox. Those paradoxes now strike me as relics of a time when Humean empiricism and logic were thought to be the best approaches to scientific theory. Harré and Madden pioneered a better view.