Many naturalistically-minded philosophers want to accomplish a naturalistic reduction of normative (e.g. moral and epistemic) claims. Mindful of avoiding the naturalistic fallacy, such philosophers claim that they are not reducing moral and epistemic concepts or definitions. Rather, they are only reducing the extension of these normative terms, while admitting that the concepts possess a normative content that cannot be naturalistically reduced. But these philosophers run into a serious problem. I will argue that normative claims possess two dimensions of normativity. I (...) will further argue that certain of the reductionist’s commitments require that these two dimensions of normativity be given a naturalistic reduction, while the other of the reductionist’s commitments make such a reduction impossible. Thus, the reductionist’s commitments both require and forbid a reductionist account of morality and epistemology. Thus, as we will see, reductionism is torn between two incompatible requirements, and must fail. (shrink)