1. Kant's theory does not provide one with any guidance in how to decide between apparently conflicting duties--e.g., a duty to one's family and a duty to the community or to God.
2. Kant says that the moral worth of an act is determined by it being from duty alone.
(i) But isn't an appeal to one's duty the 'last resort'? Isn't, for example, a motive of generosity or love a superior moral motive?
(ii) Acting from duty is only a stage in moral development
(iii) Isn't it better not to be tempted to do evil than to be tempted and then, out of an exercise of will, overcome the temptation out of duty?
(iv) What about acts 'above and beyond the call of duty'? If such acts exist, mustn't Kant either deny that heroic acts are moral or make heroic acts a duty, which robs these acts of their heroic quality and demands too much of human beings?
(v) Inclination has moral worth. Some people cultivate their benevolent impulses and some people don't. And if we do, and act benevolently as a result, shouldn't we get moral credit for this? (Hospers)
3. Kant believes that the principle of morality--the "categorical imperative"--has the form of a universal law.
(i) Doesn't Kant's "categorical imperative" tell us only what we shouldn't do, but not what we should do or what we are allowed to do?
(ii) Suppose I can universalize my maxim. Does this mean that my action is morally justifiable?
(iii) Aren't there good ways of acting which cannot be expressed in the form of a universal law?
(iv) Suppose I cannot universalize a maxim. Can I be sure that the corresponding action is immoral? What if I have a situation where, beyond doubt, the evil consequences far outweigh whatever good might be done? (Dostoevsky)
(v) Couldn't I so phrase a maxim with implicit exceptions, so that I (and anyone in my situation) could do pretty much whatever I (or others) want?
4. "Kant's ethics is an ethics for angels--for perfectly rational beings--not for human beings."
5. On Kant's view, no acts are good or bad in themselves and the consequences of an action do not affect the goodness or badness of that act. If, therefore, the morality of an act depends on (subjective) motive alone, doesn't this mean that the morality Kant proposes is, in the end, subjective?
6. Kant's ethics does not allow us to know whether we are acting morally. We never know if we are doing our duty. All we can be certain of is that we are acting in accord with our duty. In fact, not even this much may be true--we can say only that we are acting in accord with what we believe is our duty.
7. Kant's categorical imperative is based on reason. But sometimes rational people disagree about what is rational. Therefore, we can never be sure that there is a categorical imperative (binding on all rational beings) and, in particular, what this imperative will require of me in any particular case.
8. Kant says that we must never use another merely as a means. But, assuming that there is a God who created all beings, can't he do what he pleases with us, short of contradicting his own attributes?
9. If God exists, then we are subject to God's laws. Therefore ethics cannot be based on autonomy.
10. "A will that binds itself is no more bound than a person who locks himself in a house but still holds the key in his hand." If ethics is to have any meaning, however, we must be bound by something outside of ourselves. Thus, if ethics were based on autonomy, Kant's view would empty obligation of all meaning. Hence, ethics cannot be based on autonomy.
11. The only way of knowing what we can do, in Kant's system, depends on a prior knowledge of what we ought to do (as ought implies can). Moreover, on this view, the value of other people is, at best, indirect. Therefore, this is inadequate both as a basis for knowledge of reality and as a moral theory.
12. Kant confuses "freedom of choice" and "independence" (i.e., that to have free will one must be autonomous). But the requirement of the former does not involve requiring the latter. So there is no justification for Kant's principle of autonomy.
13. Kant is a closet consequentialist. The categorical imperative demands that an action be morally prohibited if "the consequences of its universal adoption would be such as no one would choose to incur" (Mill). Moreover, suppose I do choose to will the consequences. According to Kant, then, everything is OK.