Frankfurt, Like Stace, Is a Compatibilist

Frankfurt, like Stace, is a compatibilist. But whereas Stace and most compatibilists defend their position by a controversial hypothetical interpretation of the formula "S is free just in case S could have done otherwise," Frankfurt offers a theory of the will to account for our notion of freedom. What distinguishes humans from other animals is our ability to deliberate and choose courses of actions. The strategy goes like this: Both animals and humans have straightforward, or first-order, desires-for example, desires to eat, to be comfortable, and to sleep-but whereas animals act directly on their wants, humans can weigh them and accept or reject them. For example, Joan may have the first-order desire to smoke a cigarette, but she may also want to be healthy. She compares the two desires and forms a second-order desire, say, to refrain from smoking based on her desire to remain healthy. But because it is possible that she may have the second-order desire to refrain from smoking without wanting to act on it, there is one more step in the process. She must make her desire her will, her volition, and be committed to act on the desire not to smoke. A person must identify him- or herself with the second-order desire and thereby make it a second-order volition. For Frankfurt, then, free actions are those caused by second-order volitions.
-Frankfurt says that what humans have that no animal has is a large brain.