This short book by Ralph Walker (58 pages) serves as a nice introduction to Kant’s moral philosophy. Although it left me with more questions than answers – perhaps a good thing for philosophy – it did provide a broad overview of Kantian ethics that will be useful background information for future reading.

Walker divides the book into four short chapters: Moral Law, Duty, The Categorical Imperative, and A Phantom of the Brain? I will briefly summarise each before providing some of my own critical commentary.

Walker begins by describing Kant’s concept of the moral law. This is useful for understanding just how ambitious Kant’s moral philosophy is. A useful analogy here is to think of a scientific law: something that is discoverable through reason and applies everywhere, all the time, to everything and everyone. Similarly, the moral law holds “for all rational beings in general; and not just under contingent conditions and with exceptions, but absolutely necessarily” (Kant). Morality is universal and objective.

A key difference between Kant and other philosophers is that morality is an end in itself. Whereas some philosophers would argue that morality is valuable because it promotes happiness, Kant maintains that morality is a good in itself. This is what Kant means by categorical. Morality is categorical because it is its own end. In Walker’s words: “moral requirements are automatically reasons for action: they are categorical imperatives”. Once we recognise something as moral we do not need to ask any further questions about whether we should act.

It is our ethical duty to carry out the moral law – the subject of Walker’s second chapter. What does it mean to act dutifully? Kant says that “duty is the necessity of acting out of respect for the law”. By respect he means the fact that we recognise the moral law as being perfectly rational and something that we ought to follow, regardless of other considerations.  

This last point is absolutely crucial. Consider the analogy of a public servant who carries out the orders of government regardless of whether they agree or not. It is simply their duty to implement government policy. Likewise, it is our duty to follow the moral law. A public servant who carries out government policy because they agree with it is not acting dutifully. Similarly, an individual who engages in acts of charity to make themselves feel good or boost their resumé is not acting morally per se; their actions are correct, but not morally praiseworthy.

So far we have a picture of Kant’s moral philosophy as being rational, universally valid and something that we carry out dutifully. It is an austere system. But what about its actual content? What does Kant think the moral law actually says?

That is best summarised through the categorical imperative: “act only on that maxim through which you can at the same time will that it should become a universal law” (Kant). It is important to note that Kant uses the word maxim, not action. Kant is talking about the principles behind our actions (maxims), not the actions themselves. Another clarification to make is that “will” here means to rationally want something to be the case. Finally, by “universal law” Kant means a law of nature, such that it would be applicable at all times and all places.

With these clarifications in mind we can reformulate the categorical imperative in laymen’s terms. A principle of action is wrong if it is irrational to want all other people at all times to also observe that principle. For example, it is irrational to lie for the purposes of cheating someone, because if everyone lied for this reason then promises would hold no weight and it would be impossible to make promises. To deliberately lie in order to cheat someone relies on us knowing that this is wrong, because we simultaneously hope that other people will not lie so that we can continue to exploit the social institution of promising.

In Walker’s words: “I seek to exploit the practice of promising, and so I will that the practice should continue. Yet I also seek to will something inconsistent with that”. The practice of lying is self-contradictory and irrational, and by extension immoral (because morality is perfectly rational).

Kant’s ethical system is clearly very demanding. Not only does it require us to rationally know the moral law and how to apply it in each situation, but it presumes that we are capable of following through on this knowledge. Kant assumes that knowledge of morality is sufficient for our acting morally. This is because Kant thinks humans are free in a very strong sense of the term. Human rationality is capable of grasping things outside the empirical causal order of things. Ethical principles, for example, do not exist empirically within the sensible world. And yet we are capable (according to Kant) of having our actions determined by rational principles.

Kant says that the very fact that we recognise moral principles as reasons in themselves for acting goes to show that we are capable of being influenced by things outside the empirical chain of causation. I completely disagree. It is one thing to say that we recognise moral principles as reasons for action, it is quite another thing to say that such recognition is why we act. I recognise rationally that I should not drive over the speed limit, but is it my rational recognition that stops me from speeding, or my emotional fear of being injured? For me, clearly it is the latter. It is our passions that motivate us, not our reasons. If you disagree, please do let me know.