This paper advances a reductive semantics for ‘, ought’,and a naturalistic theory of normativity. It gives a unified analysis of predictive, instrumental, and categorical uses of ‘, ought’, : the predictive ‘, ought’,is basic, and is interpreted in terms of probability. Instrumental ‘, oughts’,are analyzed as predictive ‘, oughts’,occurring under an ‘, in order that’,modifier (the end-relational theory). The theory is then extended to categorical uses of ‘, ought’, : it is argued that they are special rhetorical uses of the instrumental ‘, ought’, . Plausible conversational principles explain how this end-relational ‘, ought’,can perform the expressive functions of the moral ‘, ought’, . The notion of an ‘, ought-simpliciter’,is also discussed.