Ravenhood

So a law of nature which said, say, that Ravenhood is causally linked with blackness would entail both All ravens are black and All non-black things are non-ravens, but would not entail a law linking non-blackness with non-ravenhood.

If this could be shown, the above statement would be systematically related to other statements about ravenhood in particular and the genetics of feathered creatures in general.