Anchor: economy of truth may have lost its purity, but it retains considerable utility.
Entailed: Economy of truth isn't pure but it still has utility.
Contradiction: Economy of truth is both pure and of considerable utility.
Contradiction: The boys play in the pond.
Contradiction: There are at least two people in the group.
Contradiction: The hallway is crowded.
Contradiction: He sees no reason to change it because his life is comfortable.