 On the basis of thinking about these examples involving “water” and “cube”, a person might think that whether rational intuitions have a small or a large role in discovering the essential nature of normative concepts, and other concepts of interest to philosophers, depends on whether those concepts are like the concept of water or instead like that of cube. But Peter Railton’s view that normative terms are natural kind terms allows for a large role for rational intuitions in determining their reference-fixing descriptions.