Yes, non-determinism seems necessary to have human action and therefore, economic theory.
Murray Rothbard takes Aristotle’s position that human nature includes volition. Take a look at his monograph, The Mantle of Science:
http://mises.org/rothbard/mantle.asp
Ludwg von Mises takes the “softer”position that natural sciences have not as yet provided a materialistic explanation of human action and, given our ignorance, we must treat human action as if it entails volition.
Take a look at his book Human Action, pp. 105-106.
http://library.mises.org/books/Ludwig%20von%20Mises/Human%20Action.pdf
