Full Idea
It is because ravens are birds that it makes sense to contemplate the possibility of a lawful relation between their species and their colour.
Gist of Idea
It is because ravens are birds that their species and their colour might be connected
Source
Rom Harré (Laws of Nature [1993], 5)
Book Reference
Harré,Rom: 'Laws of Nature' [Duckworth 1993], p.110
A Reaction
Compare the 'laws' concerning leaf colour in autumn, and the 'laws' concerning packaging colour in supermarkets. Harré's underlying point is that raven colour concerns mechanism.
Related Idea
Idea 15890 Non-black non-ravens just aren't part of the presuppositions of 'all ravens are black' [Harré]