 One reason the constructive empiricist would be well-advised not to embrace the Argument from Underdetermination, then, is that it goes against a voluntarist position in epistemology. (This point is clearly made by Van Dyck 2007, 19–22, and agreed to by van Fraassen 2007, 347.) By the voluntarist’s reckoning, going beyond the evidence to the extent that one chooses to believe in the truth of a theory, both in its observable and unobservable aspects, could very well be rational.