Reason and Passion

Since Aristotle, the human being has been defined as a ‘rational animal’. We are animals, since this just means that we are animate (we move), but we are different from other animals because we are rational. But what is rationality or reason?

Hume’s conception of reason is that it is the ability to calculate, to do what computers do. But a computer or calculator cannot tell you what is good or right or wrong (unless it has been programmed to do so by a human being). Judgements of beauty or morality or goodness of any kind depend ultimately on passion or feeling. But reason plays an important part. Only humans have a moral sense, and this is not just a matter of valuing whatever feels good. To know what is morally good I must think: I must abstract my moral sense from my particular prejudices and desires. Morality is distinctively and universally human, and it does involve thinking, but it is not, strictly speaking, a matter of reason, according to Hume.

Kant disagrees. His conception of reason is much fuller or richer. Reason is closely related to freedom of the will, and sets us apart from computers and other machines as well as from other animals. Reason does not just tell us how to get what we want; it wants things itself. Reason values reason, and there are some things that can rationally be willed or wanted, and others that cannot. Hume famously said that it is no more rational to prefer the scratching of one’s finger to the destruction of the world. (It might be insane not to, but it is not irrational, according to his definition of rationality). Kant disagrees. It is irrational, contrary to free will, contrary to humanity, contrary to nature, to will the destruction of the world, and therefore the destruction of free will, humanity and nature in general. Reason can and should rule over the passions.

What would an existentialist say? They all say that what we choose or value or commit ourselves to is a purely subjective, individual decision. Reason does not dictate our path through life. But they also see us as being distinct from other animals. Our freedom is distinctive. We can (and must) choose. And some choices are better than others: Kierkegaard seems to believe that an aesthetic or ethical life is doomed to frustration, Nietzsche is contemptuous of the life of the underman, and Sartre hates bad faith and values art. All value reflection highly and seem to think that only through reflecting on our lives can we find meaning. So they agree with Kant that thinking and free will are of the utmost importance.

The similarities here are as striking as the differences. All these people are part of the same Western tradition that, whether humanist or Christian, puts human beings above other animals. J.S. Mill’s higher pleasures are relevant here too. Morality, the ability to think, and free will are the main ingredients of what sets us apart. Whether the disagreements between these philosophers are purely semantic or genuinely substantive is up to you to decide. The idea that there is no significant moral difference between us and other animals is one that only a few Benthamite animal rights activists believe in, and this is a very recent idea.