According to an accepted view of the nature of evaluation, which many trace to Hume, knowledge does not provide us with the criteria for judging whether something is good. For this, it is said, we need something like a pro-attitude such as C. L. Stevenson argues for, or a decision such as R. M. Hare argues for. Some act of the will is required to create the criteria for evaluation. I shall argue against this view. I shall argue that the (...) criteria for evaluating something are identical with the criteria for classifying it and that, therefore, the knowledge which provides us with the criteria for classification provides us with the criteria for evaluation.In Section I, I give a brief account of the way in which knowledge provides the criteria for a classification and the significance of borderline cases and degree differences in classification. In Section II, I develop the idea of degree differences in classification and tie it to the idea of evaluation. In Section III, I defend my account of evaluative criteria by contrasting it with R. M. Hare's account, and I argue that the criteria for the class concept of man are at the basis of moral evaluation. I end with a brief illustration of my thesis from Kant's Metaphysics of Morals. (shrink)