Finish discussion of Wason's 4 card problem.
Opposites can both have some truth.
Bohr realized that this finding in quantum physics had implications that went beyond physics and applied to psychology and philosophy as well. It suggests that opposites are actually very similar to each other. In five minutes, list a difference for as many pairs as possible. You sleep in a hotel, but not a sock. The idea of complementarity can be applied to methods of understanding the world.