White and I evidently have a very different understanding of Kant’s ethics. Some of the points on which we differ are well known areas where Kant scholars (of which I am not one) differ. But some of White’s interpretations seem to me to be idiosyncratic to him, and I see no basis for them in the texts.
Among these is White’s view that Kant thinks that duties often conflict and that, when they do, imperfect duties can sometimes trump perfect ones, because they can sometimes have stronger grounds of obligation. In my first post I expressed my surprise at this idea, and I asked what texts White thinks support this surprising interpretation. In White’s response, he pointed me to Metaphysics of Morals Ak 6:224. Here’s what I take to be the relevant portion of what Kant says there:
A conflict of duties would be a relation between them in which one of them would cancel the other (wholly or in part). But since duty and obligation are concepts that express the objective practical necessity of certain actions and two rules opposed to each other cannot be necessary at the same time, if it is a duty to act in accordance with one rule, to act in accordance with the opposite rule is not a duty, but even contrary to duty; so a collision of duties and obligations is inconceivable. However, a subject may have, in a rule he prescribes to himself, two grounds of obligation, one or the other of which is not sufficient to put him under obligation, so that one of them is not a duty. When two such grounds conflict with one another, practical philosophy says, not that the stronger obligation takes precedence, but that the stronger ground of obligation prevails.
Far from saying what White would have him say, Kant says that genuine conflicts of duty are impossible (indeed inconceivable). If a person thinks she is in such a conflict, it is because one of more of the rules she takes to be a duty is not really a duty at all, because it is based on some “ground of obligation” that is insufficient to actually obligate her. One or both of the conflicting rules must me a mere maxim (viz. “a rule that the agent himself makes his principle on subjective grounds”).
I take it that the following would be an example of the sort of conflict Kant had in mind. Back when I was a teenage blues guitarist, I made a rule for myself that I would take advantage of every opportunity to play for an audience. Happily, a local bar converted itself into a blues venue for a time, and I established myself as a regular at their jam sessions. I didn’t drink there, no one ever asked for any ID, and it never occurred to me that minors might not be welcome. But then, one day, while I was chatting with the manager and about to go onstage, he said “You’re over 21 right?” in a tone that implied that I shouldn’t be there if I wasn’t. So my rule of taking advantage of every opportunity to perform had now come in conflict with the rule that prohibits lying. The basis of the former rule was my decision that taking every opportunity to play is a good way to develop my talents. According to Kant, I have an obligation to develop my talents. But I don’t have an obligation to specifically develop my talent at guitar, nor to develop it by playing at every single opportunity. The rule that I should develop that talent in that way is a mere maxim, and its grounds of obligation was a decision I made that did not actually obligate me. By contrast, the rule prohibiting lying is a duty that Kant thinks I can grasp a priori to be obligatory. Therefore, I had to be truthful, even if it meant violating my rule to seize every opportunity to perform.
If something is really a duty, whether perfect or imperfect, it has an authoritative ground of obligation—namely the fact that acting contrary to it would be acting on a maxim that I cannot will to be a universal law of nature. Kant thinks that it’s impossible for conflicting rules to have this ground of obligation, so he thinks duties can never conflict.
Perfect duties command one never to take certain prohibited actions (such as lying), whereas imperfect duties command one to take certain actions in at least some of the circumstances when taking those actions would not run afoul of one’s perfect duties. Thus the imperfect duty to develop one’s talents commands one to find some ways to develop some talents within the sphere of activity permitted to you by your perfect duties to refrain from lying, or euthanizing yourself, or having sex for pleasure, or doing any of the other things that Kant thinks we can each tell a priori that we are absolutely obligated never to do. Any specific rules I make for myself about how to develop my talents (or about anything else) are applicable only within the sphere in which duty permits me to act. Laws instituted by a government that has legitimate authority over me are intermediate between duties and the rules I make for myself. The government has this authority in virtue of the duties to which I, my fellow citizens, and the lawmakers are all subject, and there are bounds on this authority—most notably, it doesn’t extend to laws compelling me to violate my duties. So if the government passes a law mandating that I lie, or prohibiting me from ever aiding the needy, I’m not obligated to follow the law. But if the government passes a law preventing me from hanging out in bars until I reach a certain age, I am obligated to obey, even if it conflicts with my self-made rules for developing my talent on guitar.
Now, let’s consider the infamous case of the murderer at the door inquiring after the location of his intended victim, who is hiding in my house. I have an imperfect duty to promote the wellbeing of others, and it commands me to do what I can, consistent with my other duties, to prevent innocents from being murdered. One rule I might adopt for myself (or even that might be legitimately legislated by government) would be to shelter intended victims in my house whenever possible. Perhaps it’s by following this rule that I got into my present predicament. But since I have a perfect duty not to lie, I can’t get out of the predicament by telling the murderer that the victim is elsewhere. I must find some other means. I can refuse to open the door, or to answer his question. Perhaps I can stall (without lying) for long enough to give the victim a chance to escape. But, if all these options fail, then I simply have to let the victim die.
White thinks Kant reached this conclusion only because of a misapplication of his own theory. He may be right. Many have argued that a perfect duty prohibiting lying does not really follow from Kant’s basic premises. However, this is not the main fault that White finds in Kant’s application. White thinks that Kant ought to recognize that the ground of my duty of beneficence, which White thinks is “an innocent life,” outweighs the ground of my duty not to lie in this case. But “an innocent life” isn’t the sort of thing that Kant thinks can ground an obligation at all. For him, all duties have precisely the same ground—namely, one’s inability to will that that a contrary maxim be a universal law of nature—or (to put what Kant thinks is the same point in a different ways) one’s treating humanity always as an ends and never as a mere means—or one’s respecting everyone’s autonomy. Other obligations, which are subordinate to these, derive from governments and agreements and the like that arise within the context of these duties. Issues like what happens to innocents—or to anyone else—don’t enter into the picture. To be sure, we have duties about how to treat innocents, but the consequences of our actions for their lives cannot as such be grounds of obligation, because consequences are just not the sorts of things that Kant thinks ground obligations. At least, that’s how I understand Kant, and I haven’t seen any evidence from White that supports his contrary interpretation.
Kant is not the “flexible,” “commonsensical” ethicist White wants him to be. If this is the sort of view he thinks is necessary to defend his political convictions, I suggest he look to other ethicists. W.D. Ross, in particular, comes to mind. He argued that the various formulas through which Kant thinks one can determine what one’s duties are do not yield determinate answers, as Kant thought they did, to the question of what one should or should not do in various situations. Any action can be described at different levels of abstraction, such that it will be willable as a universal law under some descriptions and not under others. Lying to the murderer at the door, for example, is universal when described as “a lie told to a murderous person,” but not when descried simply as a lie. With no simple algorithm for determining one’s duty, Ross instead generates a commonsensical list of “prima facie” duties, each of which has its source in some fact of the sort that (I gather) White thinks would count as a grounds of obligation. These prima facie duties aren’t actual duties, Ross argues, because they can come into conflict with one another. To determine one’s actual duty in a given circumstance, he thinks, one must exercise a nuanced particularistic form of judgment that is reminiscent of Aristotelian phronēsis. This seems very much like the theory of judgment that White finds in Kant. (I hope to say a bit about how I understand Kant’s view of judgment in a future post.)
For my part, I don’t see this sort of flexibility as a desideratum in ethics. On this one point I’m nearer to Kant than to Ross and White. A true moral principle, I think, is an absolute that applies without exceptions within the contexts in which it arises. If you find yourself in a situation where your moral principles seem to demand conflicting actions, you need to (as Rand put it) “check your premises.” You’ll find that there is a mistake somewhere in the chain of reasoning that led you to think that one of those principles is true or applicable to the situation at hand.
Moreover, I don’t think that the sort of Rossian flexibility White finds in Kant is of any help in grounding what I think of as the key insight of the classical liberal tradition: the idea that we each have an inalienable right to life, liberty, property, and the pursuit of happiness. Kant’s best claim to have made an important contribution here is that his moral theory is rigid enough to support such inalienable rights, whereas (for example) Mill’s is not. In the end, however, I think the critics are right that no specific content about our obligations or rights follows from Kant’s framework. And I think his basic conception of morality and its role in life represents an attack on the principles from which I think our rights to life, liberty, and the pursuit of happiness in fact arise. More on this in a later post.
 Quoting from Mary J. Gregor’s translation in the “Practical Philosophy” volume of The Cambridge Edition of the Works of Immanuel Kant.
 It is worth noting that almost all of Kant’s own examples of such things, are things that all or most sensible people today think we are entitled to do. It’s true that philosophers sometimes misapply their own theories, but in Kant’s case most of the things that he takes to be obvious and paradigm duties are things that modern interpreters wishing to put a friendlier face on Kant are wont to regard as misapplications of the theory.
 See his Kantian Ethics and The Right and the Good.