Abstract In the vast literature on human rights and natural law one finds arguments that draw on science or mathematics to support claims to universality and objectivity. Here are two such arguments: 1) Human rights are as universal (i.e., valid independently of their specific historical and cultural Western origin) as the laws and theories of science; and 2) principles of natural law have the same objective (metahistorical) validity as mathematical principles. In what follows I will examine these arguments in some detail and argue that both are misplaced. A section of the paper will be devoted to a discussion of arguments relying on the historical and cultural specificity (and intrinsic superiority) of Western science. The conclusion is that both science and mathematics offer little help to anyone wanting to make use of them as paradigms of universality, objectivity, and rationality. Finally, I will draw some consequences for the idea of human rights.