Williams was not an ethical realist; unlike scientific knowledge, which can approach an "absolute conception of reality," an ethical judgment rests on a point of view. He argued that the "thick" ethical concepts, such as kindness and cruelty, express a "union of fact and value." The idea that our values are not "in the world" was liberating: " radical form of freedom may be found in the fact that we cannot be forced by the world to accept one set of values rather than another."