Anchor: If the wage premium is accurately calculated by Professor Wachter, it would be difficult to defend the U.S. postal monopoly on purely economic grounds.
Entailed: If Professor Wachter is correct with the wage premium amount, it'll be hard for the postal service to be defended.
Contradiction: The postal service's monopoly on economics was incorrectly calculated bu Professor Wachter. 
Contradiction: That man is playing with the fog
Contradiction: Being strangers is safe because
Contradiction: A famished person is cooking a meal for his family.
Contradiction: The slave master had a lot of facial hair.