Kantian Ethics, Part 1: Kant vs. Hume

I've been thinking for awhile now that it would be helpful, for the sake of the discussions about ethics on this blog, to devote some time to explicating Kant's thinking about the nature and foundations of morality, as well as some of the neo-Kantian approaches that have been pursued since. I begin this endeavor in the current post, by thinking about the context against which Kant developed his moral theory. Specifically, I want to locate Kant's moral theory in relation to the thinking of his predecessor whom Kant credited with "waking" him from his "dogmatic slumber"--the empiricist philosopher David Hume.

One of the most significant features of Kant’s moral philosophy is its status as a response to Hume’s dictum, “Reason is a slave to the passions.” Hume’s idea here--an important challenge to the dominant thinking about morality that preceded him--has since seeped deeply into the modern naturalist worldview. The basic notion is this: human reason cannot tell us how we ought to behave on its own. Rather, it can only tell us how to achieve certain aims, given that we want to achieve those aims.

In other words, my appetites and desires—influenced by inheritance and upbringing—lead me to value certain ends or goals; and then my reason can tell me how to achieve those ends or goals. With the right information and the proper degree of impartiality, I can reason out the most efficient pathway to get what I want. But absent some goal given to me by my “passions,” reason is not action-guiding at all.

In Kant’s language, Hume thinks that reason is only capable of generating “hypothetical imperatives”: injunctions on action of the form, “If you want X, then do Y.” But such imperatives are not action-guiding by themselves. Tell me that to avoid tooth decay I should brush my teeth, and I’ll brush my teeth—if I want to avoid tooth decay. But suppose, for some reason, I want my teeth to rot out of my mouth (perhaps I hate myself and have heard that dental health and hygiene is directly correlated with longevity). In that case, the “hypothetical” or conditional imperative doesn’t apply to me.

So, Hume thought that reason could only generate hypothetical imperatives. It could not, on Hume’s view, generate “categorical imperatives,” which have the form “Do Y (regardless of your desires).” Put another way, Hume thought that reason could not establish unconditional laws for behavior, rules for behavior that it is rational for us to act on regardless of our contingent appetites or desires. Reason can tell us that action A is the most efficient way to get outcome O, but it cannot tell us that we ought to pursue O, let alone that we ought unconditionally ought to pursue some action A regardless of its outcome. All rational reflection on action is, for Hume, means-ends thinking: if you seek a given outcome O, action A is the way to get there.

For Hume, this meant that if any reason-generated principles for behavior applied universally to all people, it would be because certain desires were universal. Perhaps all people desire happiness. If so, then a dictum of the form, “If you want to be happy, do Y” would be universal in its scope. It would apply to all people, but only because all people just happen to subjectively value their own happiness.

It was a short step from Hume’s dictum to 20th Century variants of ethical subjectivism—that is, to views of ethics which hold that moral norms apply to us only if they’re in line with our subjective values. While a certain uniformity of subjective values might be explained in terms of species-wide facts of human biology, and more localized uniformity might be achieved through socialization or cultural conditioning, there are no values that it would be intrinsically irrational to have (or not to have). And there are no moral prohibitions or requirements that apply regardless of people’s subjective values.

Kant thought all of this was nonsense. He was convinced, in contrast with Hume, that reason could place requirements on action that apply regardless of our subjective desires, and that reason could demand that we value certain things. Put more simply, Kant was convinced that there are some things that it is irrational for you to do even if doing it conflicts with none of your actual wants or desires. There is, according to Kant, at least one Categorical Imperative (upper case) that reason lays down. Obedience to this Categorical Imperative is an absolute condition for being rational in one’s practical life.

In fact, Kant thought there was indeed but one Categorical Imperative of reason—a very general principle that has a wide range of implications. In other words, he thought reason gives to us a fundamental principle of morality, from which all our specific moral duties derive. But he also thought that this fundamental principle could be formulated in different ways. Later commentators have often puzzled over these formulations, because they don’t seem to be different formulations of the same principle. Rather, they appear to be different principles. But that is an issue I probably won't take up in this series of posts.

In my next post, I will look at the first “formulation” of Kant’s “Categorical Imperative,” with an eye towards doing two things: first, explicating what, exactly, the principle is requiring of us; second, explaining why Kant thought that this principle was a demand of rationality, regardless of our desires.