My answer has always been No, but partly thanks to his questioning, I see this issue more and more clearly. Among all sciences math is most valid (effective) in physics and becomes less so as the science concerned becomes less "physical". In this spectrum of validity of math psychology is at the far end. Economics is a close one to psychology since both involve the human mind. So I always wonder what Nash's math really has to say with economics since I think a mathematical model is helpless in economics.
See what 驴大師 has to say.