knowing in humans for Aquinas. A moral claim such as “it is wrong to do evil,” Aquinas reasons, cannot be empirically established. (Many modern philosophers agree with this point when they argue that logically you cannot derive an “ought” from an “is.” Just because drilling a tooth, for example, “is” a source of pain does not mean that we “ought” not to drill teeth.) The claim that “it is wrong to do evil” is not provable by empirical evidence; it is a truth known or intuited by the intellect.