This paper responds to Professor John McMurtry, primarily to his critique of my recent book, Economics as Moral Science. Although agreeing with my attribution of a "moral a priorism" to orthodox or neo-classical economics, McMurtry takes issue with my "conversion thesis", that an a priori, ethically committed theory can be transformed into a testable empirical science of actual behaviour through the application of institutional constraints to individual motivations. McMurtry views such a thesis as "logically possible but morally abhorrent". In so (...) doing, he ascribes a version of economic determinism to me which, he claims, leads me to mistakenly understand the neo-classical paradigm as circumscribing the "boundaries of reality itself" and thereby entrenching the life-destructive values presupposed by this paradigm. I reject such a reading of Economics as Moral Science and explain the manner in which it is inconsistent both with the theoretical substance and practical agenda of my work. I propose that the irreducible basis of disagreement remains one wherein I believe that a more radical reform of the capitalist market order is mandatory to establish more defensible moral ideals than does McMurtry. My reply closes by recommending a constitutional partitioning of material goods such that we may more securely act outside the ethical constraints of neo-classical theory. (shrink)