What should I do? As long as I am aware of the relevant facts of the situation and deliberating soundly, Bernard Williams argues that I should do what I want to do. It makes no sense to say that there are reasons that are fixed objects of concern, or values, that exist for an agent regardless of what she is in fact motivated to do. Reasons, for Williams, are hypothetical. I argue that he takes this view of practical reason because of a prior answer to the question “How should I live?”. A universal account of the good life would mean an account of values, or interests, that all human beings should have. Williams thinks it is not possible to give a universal account of the good life for human beings; any such account must be constructed out of the particular reasons of a community. But, he takes a constructivist view of the good life because he thinks that to be universal an account of the good life would have to be objective. Since objectivity cannot be achieved, he argues, neither can universality. Williams is only half right. That objectivity is not possible is inconsequential. A foundation for ethics has to be internal, but this does not preclude it being universal. I develop such a foundation based on the Aristotelian conception of human nature. A life cannot be wholly good if it is not self-respecting. Moreover, self-respect fits the framework for the specification of the good life that this foundation provides: I argue that self-respect can be shown to have a structure which provides an account of real interests - reasons that are objects of fixed concern. As such, reasons recognise rather than construct the good, making categorical reasons possible. A person can have a reason to change or act, even if reason itself cannot effect that change or action. Thus, I can be wrong about what I should do not only by being wrong about what would count as a satisfaction of my interests, but also by being wrong about what my interests are.