The Raven Paradox
The Raven Paradox is a problem for Nicod's Criterion. The statement
(1) "All non-black things are non-ravens" is logically equivalent
to (2) "All ravens are black", so anything that confirms one should
confirm the other.
According to Nicod's Criterion, a black raven is irrelevant to
(1) and confirms (2), while a piece of white chalk is irrelevant to
(2) and confirms (1).
Literature
The main source is Hempel
1945. The issues are taken up in Lipton 1993, Chapter 6.
Copyright David Chart 1997