History of Modern Ethics
Stephen Darwall
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Kant Lecture 2

I. Kant's two great foundational works of moral philosophy are Groundwork of the Metaphysics of Morals (1785) and Critique of Practical Reason (1788). These are the works where he tries to establish the fundamental principles of all ethical thought. However, these were by no means the whole of his ethical writings. In addition he wrote a two volume work that elaborated the normative ethical scheme: The Metaphysics of Morals.

II. A central organizing idea of Kant's two foundational works is freedom. Intuitively, we are free by virtue of our capacity to determine our will by reasons, by a conception of law. But, Kant argues, a free agent can do this successfully only by following the Categorical Imperative (act on a maxim only if you can will that it should likewise be acted on by everyone).

Why suppose we actually are free? Note that this is tantamount to asking, Why suppose that reason can determine the will? Why suppose there is genuinely practical reason? Kant's answer in Critique is different from what he says in the Groundwork. His Critique answer is that we have to suppose we are free because he take ourselves to be subject to the moral law. Freedom is thus a condition of being morally bound. We couldn't be morally bound and not be free.

His response in the Groundwork, however, is different. There he argues that an agent cannot act, cannot deliberate about what to do, except under the assumption that she is free, that she can determine her choices by reasons. The intuitive idea is that in deliberating we ask ourselves what to do, what reasons there are to do one thing rather than another. But in so doing we have to assume that we can determine our wills by what we regard to be good reasons.

Furthermore, the assumption that we are free, as embodied in deliberation, is all Kant insists on. This makes us really free ``in a practical sense''. Moreover, he regards this thought as fully compatible with the belief that everything we do is utterly determined. In fact, his views in the Critique of Pure Reason commit him to the position that in viewing our own and other people's actions from an observer's point of view, we must take them to be effects of prior causes. So, from a theoretical or observer's point of view, all occurrences, and hence, all actions, are fully caused, and could, in principle, be predicted if we knew their causes. But this is fully compatible with our actions being free in the sense that, from the agent's point of view in deliberation and action, we must regard our choices as determined by our reasons, and hence as practically free in this sense.

Christine Korsgaard gives a helpful illustration. Suppose we believed that our every move was fully caused and that there is an omniscient predictor who knows exactly what we are going to do. What effect should this belief have on our actions? We would still, ourselves, face the question of what to do. This question would in no way be undermined or answered by our knowledge that what we end up doing will have been be fully predictable. To decide what to do, even if we believe what we will do is fully predictable, we simply ignore, not to say repress, this belief, and consult what reasons there are for doing one thing rather than another. That is we undertake to determine our wills by what we can regard as reasons to act.

III. Enough stage-setting. Let's get into the text. We need to begin with some definitions.

``Practical principles are propositions which contain a general determination of the will, having under it several practical rules. They are subjective, or maxims, when the condition is regarded by the subject as valid only for his own will. They are objective, or practical laws, when the condition is recognized as objective, i.e., as valid for the will of every rational being.''

So practical principle is the genus, and subjective principles, or maxims, and objective principles, or practical laws, are species of this genus. Any ``general determination of the will'' is a practical principle (i.e., something of the form ``in circumstances C, I will do A''). And if the agent regards this as ``valid'' for his will only, and acts on it under that thought, then it is merely subjective. If, however, he ``recognizes'' it as ``valid for the will of every rational being'', then it is objective, or a practical law.

You will no doubt note, here, that nothing is said about what makes a practical principle ``valid'' for every, or even a, rational being. However, if a practical principle is a practical law, then it states a condition of will determined by reason alone. And because it expresses this ``objective necessitation'' it presents itself to us as an imperative, as what we ought to do. (18)

Of such oughts or imperatives, two kinds exist: hypothetical and categorical. A hypothetical imperative presents an action as necessary to achieve a (contingently) desired purpose. E.g., if you want to understand Kant, you must read him more than once. A categorical imperative, on the other hand, presents an action as necessary, not because it will achieve the agent's contingent ends, but in itself. As Kant puts it, they ``must completely determine the will as will''. (18) ``… tell a man that he should never make a deceitful promise; this is a rule which concerns only his will regardless of whether any purposes he has can be achieved by it or not.'' (19)

IV. With these definitions we can look to Kant's ``proofs'' of Theorems I and II.

A. Theorem I. ``All practical principles which presuppose an object (material) of the faculty of desire as the determining ground of the will are without exception empirical and can furnish no practical laws.'' (19)

By a practical principle ``presuppos[ing] an object (material) of the faculty of desire'' Kant evidently has in mind the case where an agent determines his will in some general way (in C, I will do A) on the grounds that he desires some particular thing: ``When the desire for this object precedes the practical rule and is the condition under which the latter becomes a principle.'' But in this case, it is a contingent matter whether any particular rational being has such a desire: ``we cannot know, a priori, of the idea of any object, whatever the nature of this idea, whether it will be associated with pleasure or displeasure or will be merely indifferent.'' (20) Therefore, no such principle can be (regarded to be) a practical law. Q.E.D.

B. Theorem II. ``All material practical principles are, as such, of one and the same kind and belong under the general principle of self-love or one's own happiness.''

Kant's reasoning here shows him to be a psychological hedonist. Motivation rooted in contingent desire is based on agreeable feeling, and any such desire is ultimately a desire for some agreeable feeling or other.

He gives an interesting, but curious (indeed almost offensive) argument on p. 22, to the effect that, if our desires didn't have some such homogeneous stuff as object, we wouldn't be able to choose between conflicting desires. ``Otherwise how could … affected''.

Now, in fact, I think that this implausible psychology is really beside any central point that Kant wants to make and that he could as well give it up. The point he needs to rely on is that no contingent desire, whether its object is agreeable feeling or not, can be common to any being capable of determining the will by practical reason.

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