"Economics is the only field in which two people can get a Nobel Prize for saying the opposite thing" is true, but is not strong enough. Better:

"Economics is the only field in which two people can share a Nobel Prize for saying opposing things." Specifically, Myrdal and Hayek shared one.

From http://netec.mcc.ac.uk/JokEc.html

This just shows how amazing economics is! To be able to be so flexible and allow freedom of thought for everyone!

-Leona