Moral Internalism claims that there is a necessary connection between judging that some action is morally right/wrong and being motivated to perform/avoid that action. For instance, if I sincerely believe that it is morally wrong to eat animals, then I would be automatically motivated not to eat animals. If I sincerely believe that it is morally required for me to take care of my children, then I would be automatically motivated to take care of my children. This claim is called ‘Internalism’ (or more technically, ‘Motivational Judgment Internalism’) because in such cases, the motivation is internal to the evaluative judgment. There are different types of Moral Internalism, but we will here be concerned with the conceptual variety advocated by Hare (1952), which claims that the link between moral judgments and motivation is an a priori conceptual truth.
The fact that Internalism appears intuitively to be true specifically for moral judgments has been extremely important to moral philosophers. In response to the skeptical question: “Why should I care about right and wrong?” some ethicists have argued that the question is nonsensical, since by making judgments about right and wrong, one is automatically motivated to care about these judgments. In response to the question: “What kind of judgments are moral judgments?” philosophers going back to Hume have argued that beliefs like ‘my car is black’ or ‘today is Tuesday’ can never in themselves motivate or direct anyone to perform some action, but only in conjunction with an emotion. If one adopts this Humean Theory of Motivation along with Moral Internalism, then, as Hume states, “it is impossible that the distinction betwixt moral good and evil can be made by reason; since that distinction has an influence on our actions, of which reason alone is incapable” (Hume, 1739). In other words, since beliefs are never inherently motivating, moral judgments cannot be normal beliefs about the world. This conclusion is known as (psychological) non-cognitivism, and has obvious consequences for how we engage in moral debate and consideration.