History of Modern Ethics
Stephen Darwall
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Kant Lecture 5

I. Suppose we begin with the assumption that we are free, in the sense that we can determine the will through reasons. Can we then deduce the Categorical Imperative, the Fundamental Law of Practical Reason? How might this go? This is what Kant calls Problem II on p. 529:

``Supposing that a will is free, find the law which alone is competent to determine it necessarily.

Since the material of the practical law, i.e., an object of the maxim, cannot be given except empirically, and since a free will must be independent of all empirical conditions (i.e., those belonging to the world of sense) and yet be determinable, a free will must find its ground of determination in the law, but independently of the material of the law. But besides the latter there is nothing in a law except the legislative form. Therefore, the legislative form, in so far as it is contained in the maxim, is the only thing which can constitute a determining ground of the [free] will.''

How is this reasoning supposed to work? Consider the very idea of an agent acting for [what she regards to be] reasons. Now, while an agent may of course take her desires to provide her with reasons, her being moved by a desire is not the very same thing as her being moved by [what she regards to be] a reason. Think back to our heroin addict. Suppose she regards her addiction as a compulsion she is in the grip of, as something which gives her no reason to take heroin. Here she has a strong desire for heroin, but, as she judges it, no reason to take it. She will take it for a reason, she will have some reason for taking it, only if there is something she can regard as a reason to take it.

But, as we have noted before, this seems to commit her to a universal proposition. Can she coherently think that a feature of the situation provides her with a reason to do something, but would not for someone ``relevantly like her'' in a situation ``relevantly like hers''. It seems she cannot. She must be prepared to think that it is because she is an agent (of some relevant kind) in a situation of some relevant kind that she should so act. That is, she must think there to be some universal law which applies to her in this situation that recommends her so acting. For her to act for reasons, therefore is for her to be committed to willing her action as an instance of some (universal) law.

II. Kant assumes that, since no desire for any object is necessarily part of rational agency, willing an action as an instance of a law applying to all agents cannot be identical with determining the will through the desire for some object. But what alternative is there? Kant seems to think that the only alternative is the agent's determining her will by a particular maxim being conditional on the agent's being prepared to will her maxim as universal law.

The picture, then, is this. An agent is inclined toward adopting particular maxims by his particular, contingent psychological makeup. Perhaps he desires the welfare of others. In this case he is moved to adopt maxims that seem likeliest to promote this. Or perhaps, like Kant's self-interested homo economicus of 523f., he desires only to increase his property, and so is moved to adopt a maxim: ``I will increase my property by every safe means.'' Now, just by having these maxims, so conceived, an agent is not yet acting for reasons. To do that she has to regard her maxim as rooted in universal law, and she must will her acting on the maxim as prescribed by such a law.

Now, being moved to adopt, and be guided by, a maxim by a desire for some object---whether for the welfare of others, or for the increase of one's property, or for some other thing---is not the same thing as being moved to determine the will by a maxim because this is prescribed somehow by universal law. An agent can be doing the latter only if she is prepared to will her maxim as universal law. Thus Kant concludes what he calls, in the Groundwork, the Categorical Imperative:

Act only on maxims that you can at the same time will to be a universal law.

III. The argument seems to depend on the assumption that the only alternative to acting on the CI is acting from a desire. Is this so? What if my motivation is not a desire that my interest be promoted (by me or someone else), but rather my acceptance of an egoistic norm of action. Will the norm pass the CI test? On the one hand, since I am not following this maxim in order that my interest be promoted, we will not necessarily get a contradiction in the will between a private end (my own interest) and what I will when I will that everyone do what is in their interest (supposing this is not in my interest). On the other hand, the principle itself tells me only to will what is in my interest, so if it is not in my interest that everyone act on this maxim, then my maxim tells me not to will its universalization. Suppose that, for this reason, my maxim fails the test. Why might it not still be a practical law, nonetheless? I certainly seem to be able to treat it as a practical law.

IV. Kant doesn't deal with this question in the Critique in a way that he does, at least implicitly, in the Groundwork. There the idea seems to be that the alternative we are supposing, that a principle might simply be a practical law, quite independently of whether a free agent could legislate or will it, is unacceptable because it implies heteronomy and is inconsistent with autonomy, ``the property the will has of being a law to itself''. (GR440) Now there is a weak sense in which the very idea of practical law presupposes autonomy, since, by their very nature, practical laws bind any rational agent, that is, any being with a will. So it is the will itself that is the ground of obligation. Nothing our norm-egoist thinks, however, need be inconsistent with that. He accepts egoism as a norm that binds all rational agents (all wills). But it is clear that Kant has in mind something stronger by autonomy, namely that the will is a law to itself, in the sense that following the practical law (the law to which any will is subject) can consist in nothing more than the exercise of the capacities that are intrinsic to will . And here Kant's idea that, from this perspective, nothing is given to will---either empirically (through desire) or a priori (by some kind of rational intuition). Free agency is a formal rather than a material or substantive capacity.

Access to the practical law can only come through the exercise of free will, and this requires that practical law must be capable of being legislated by each will. Hence the CI test: ``Act only on maxims you could will as universal law.''

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