6 Kantian Deontology

Joseph Kranak

Immanuel Kant (1724-1804) by Johann Gottlieb Becker via Wikimedia Commons. This work is in the public domain.

Relative to most other philosophers, Immanuel Kant (1724-1804) was a late bloomer, publishing his first significant work, The Critique of Pure Reason, in 1781 at age 57. But this didn’t slow him down, as through his 50s, 60s, and 70s, he published numerous large and influential works in many areas of philosophy, including ethics. He published two large works on ethics, The Critique of Practical Reason and The Metaphysics of Morals, but it’s his first short work of ethics, Groundwork of the Metaphysics of Morals that is his most important because it provides a succinct and relatively readable account of his ethics.

Some of the main questions that Kant’s ethics focuses on are questions of right and wrong: What makes an action right or wrong? Which actions are we required by morality to perform? Do consequences matter? Is it ever permissible to do something morally wrong in order to achieve good consequences? Is it important to do actions with good intentions? And what are good intentions? Some of Kant’s answers to some of these questions are complex, but as we will see, he doesn’t think that consequences matter and thus good consequences cannot justify wrong actions. He also thinks that intentions are important to the ethical evaluation of actions.


One of the distinctive features of Kant’s ethics is that it focuses on duties, defined by right and wrong. Right and wrong (which are the primary deontic categories, along with obligatory, optional, supererogatory, and others) are distinct from good and bad (which are value categories) in that they directly prescribe actions: right actions are ones we ought to do (are morally required to do) and wrong actions we ought not to do (are morally forbidden from doing). This style of ethics is referred to as deontology. The name comes from the Greek word deon, meaning duty or obligation. In deontology, the deontic categories are primary, while value determinations are derived from them. As we’ll see, Kant believes all our duties can be derived from the categorical imperative. We’ll first need to explain what Kant means by the phrase “categorical imperative” and then we’ll look at the content of this rule.

First, Kant believes that morality must be rational. He models his morality on science, which seeks to discover universal laws that govern the natural world. Similarly, morality will be a system of universal rules that govern action. In Kant’s view, as we will see, right action is ultimately a rational action. As an ethics of duty, Kant believes that ethics consists of commands about what we ought to do. The word “imperative” in his categorical imperative means a command or order. However, unlike most other commands, which usually come from some authority, these commands come from within, from our own reason. Still, they function the same way: they are commands to do certain actions.

Kant distinguishes two types of imperatives: hypothetical and categorical imperatives. A hypothetical imperative is a contingent command. It’s conditional on a person’s wants, needs, or desires and normally comes in the following form: “If you want/need A, then you ought to do B.” For example, the advice, “If you want to do well on a test, then you should study a lot” would be a hypothetical imperative. The command that you study is contingent on your desire to do well on the test. Other examples are, “If you are thirsty, drink water,” or “If you want to be in better shape, you should exercise.” Such commands are more like advice on how to accomplish our goals than moral rules. If you don’t have a particular want, desire, or goal, then a hypothetical imperative doesn’t apply. For example, if you don’t want to be in better shape, then the hypothetical imperative that you should exercise, doesn’t apply to you.

A genuinely moral imperative would not be contingent on wants, desires, or needs, and this is what is meant by a categorical imperative. A categorical imperative, instead of taking an if-then form, is an absolute command, such as, “Do A,” or “You ought to do A.” Examples of categorical imperatives would be “You shouldn’t kill,” “You ought to help those in need,” or “Don’t steal.” It doesn’t matter what your wants or goals are; you should follow a categorical imperative no matter what.

But these aren’t the categorical imperative. Kant believes that there is one categorical imperative that is the most important and that should guide all of our actions. This is the ultimate categorical imperative from which all other moral rules are derived. This categorical imperative can be expressed in several different ways, and Kant presents three formulations of it in The Groundwork.

The First Formulation of the Categorical Imperative

The underlying idea behind the first formulation of the categorical imperative is that moral rules are supposed to be universal laws. If we think of comparable laws, such as scientific laws like the law of gravitational attraction or Newton’s three laws of motion, they are universal and apply to all people equally, no matter who they are or what their needs are. If our moral rules are to be rational, then they should have the same form.

From this idea, Kant derives his first formulation of the categorical imperative, “act only in accordance with that maxim through which you can at the same time will that it become a universal law” (Groundwork 4:421).[1]

First, we must explain this word “maxim.” What Kant means by a maxim is a personal rule or a general principle that underlies a particular action. As rational beings, we don’t just act randomly; we devise certain rules that tell us what to do in different circumstances. A complete maxim will include three pieces: the action, the circumstances under which we do that action, and the purpose behind that action. For example, the maxim explaining why you’re reading this book, if it’s an assigned text, might be, “I will read all books assigned for class because I want to succeed in class.” Different principles could underlie the same action. For example, you might be reading this book simply to help you understand the topic, in which case your principle might be, “When I am confused about a topic, I will read an accessible text to improve my understanding.” The important point is that we are guided by general principles that we give to ourselves, that tell us what we’ll do in certain circumstances.

The first formulation, thus, is a test of whether any particular maxim should be followed or not. We test a maxim by universalizing it, that is, by asking if it would be possible for everyone to live by this maxim. If the maxim can be universalized, meaning that it’s possible that everyone could live by it, then it’s permissible to follow it. If it can’t be universalized, then it is impermissible to follow it. The logic of the universalization test is that any rule you follow should apply to everyone—there’s nothing special about you that allows you to be an exception.

To look at some examples, imagine you need money to pay off some debts. You go to a friend to borrow the money and tell this friend that you will pay him back. You know you won’t be able to pay your friend back, but you promise him nonetheless. You are making a false promise. Is this permissible? To test, we first look at the maxim underlying the action, something like, “If I need something, I’ll make a false promise in order to get what I need.” What would happen if everyone were to make false promises every time they needed something? False promises would be rampant, so rampant that promises would become meaningless; they would just be empty words. For this reason, the maxim can’t be universalized. The maxim included the idea of making a promise, but if, when universalized, promises cease to have any meaning, then we couldn’t really make a promise. Since the maxim can’t be universalized, we shouldn’t follow it, and thus we derive the duty to not make false promises.

We should note that Kant’s universalization test is not asking whether universalizing a maxim would lead to undesirable consequences. Kant is not claiming that making a false promise is wrong because we wouldn’t want to live in a world where no one kept their promises. It’s wrong because it’s not possible to universalize the maxim. It’s not possible because it leads to a contradiction. In this case, the contradiction is in the concept of a promise: that it becomes meaningless when universalized. We can see this with other maxims. If you’re thinking of stealing something, the maxim underlying this action might be something like, “I’ll steal the things I want so I can have what I want.” If everyone were to follow this maxim, then the concept of ownership would cease to have any meaning, and if nothing were owned, then how would it be possible to steal? To steal means to take someone else’s property without permission, and this is where the contradiction comes in. It’s not possible to steal if nothing belongs to anyone. Thus, it’s not possible to universalize this maxim, and we thereby get the duty that we shouldn’t steal. Both of these contradictions are what Kant calls “contradictions in conception.”

Another example Kant gives is of our obligation to help out others. Suppose you could help people but didn’t want to. Your maxim might be, “I will never help out anyone else since everyone should be independent.” If this were universalized, then everyone would be completely independent, with no one asking for, nor offering help. However, we wouldn’t be able to live in a world where no one helps anyone because we’ll inevitably sometimes need others’ help. The contradiction in this case is a practical contradiction, “a contradiction in will,” as Kant calls it. In this case, we would eventually have to break the maxim due to our need for help. Thus, from this, we get the duty that we should sometimes help out others in need.

Problems with the First Formulation

One criticism that Kant faced among his contemporaries was for his stance on lying, since he said that we always have a duty to be truthful to others (Metaphysics of Morals 8:426). His reasoning seems to be that if we were to try to universalize a maxim that permits lying, such as “I will lie whenever it’s convenient to get what I want,” then people would be lying constantly, and it would lead to the concepts of “lie” and “truth” becoming meaningless. Thus, since “lie” would no longer mean anything, it’s impossible to universalize this maxim, and thus we should never lie. His contemporaries thought there must be cases where lying is permissible, and Kant responded in “On a Supposed Right to Lie From Philanthropy.” In this essay, Kant imagined a situation that would seem to permit lying. Suppose that your friend is being pursued by someone who intends to kill him. Your friend comes to your house and asks to hide. You let him do so, and soon after, the killer is knocking at your door asking, “Is your friend inside?” Should you lie or not?

Kant asserts that you shouldn’t lie, even in these circumstances. Suppose your friend hears the killer knocking at the door and decides to flee out the back without your knowing. You lie and tell the killer that your friend is not here, and the killer leaves. Because of this, your friend and the killer bump into each other, and your friend is killed. Since your lie led to them to bump into each other, you bear some responsibility for the friend’s death. His general point is that consequences are uncertain. Importantly, Kant believes that consequences don’t affect whether an action is right or wrong, and this example highlights why: because consequences are unpredictable. The type of rational approach to ethics that Kant prefers will downplay the importance of consequences due to this unpredictability.

Another problem for the first formulation is that it’s possible to imagine maxims that can’t be universalized but that don’t seem to be immoral. For example, a stamp collector might live by the maxim, “I will buy but not sell stamps in order to expand my collection.” If everyone were to follow this, then the collector wouldn’t be able to buy because no one would be selling. This seems to lead to the implausible conclusion that collecting stamps (or collecting anything) is immoral. Since Kant says that we are to “act only in accordance” with maxims that can be universalized, then any maxim that can’t be universalized is impermissible.

Some who want to defend Kant think that the problem is with how this maxim is phrased. The maxim specifies two actions: buying and not selling. If we split it into two maxims—“I will buy stamps to expand my collection” and “I will not sell stamps to expand my collection”—the problem can be avoided. This does point to a general difficulty with the first formulation, generally referred to as the “problem of relevant descriptions,” which is that there is often more than one way to describe the maxim underlying an action. And when we formulate it some ways (like in this case with the stamp collecting) it leads to a contradiction, whereas formulating it other ways does not.

Good Will

For Kant, just doing the right thing is not sufficient for making an action have full moral worth. It’s also necessary to act with good will, by which Kant means something like the inclination to do good or what is also known as a good character. He believes that a good will is essential for morality. This is intuitively plausible because it seems that if an otherwise good action is done with bad or selfish intentions, that can rob the action of its moral goodness. If we imagine a man who goes to work at a soup kitchen to help out the poor, that seems like a good action. But if he’s going there just to impress someone who works there, then that’s less virtuous. And if he’s going there to embezzle money from the charity, the action would be morally wrong.

Less intuitive is that Kant thinks the only possible genuine good will is respect for the moral law. Arthur Schopenhauer (1788-1860) would later describe Kant’s position as, “a deed must be performed simply and solely out of regard for the known law and for the concept of duty…. It must not be performed from any inclination, any benevolence felt towards others, any tender-hearted sympathy, compassion, or emotion of the heart” ([1818] 1969, 526). That is, when you do something because it is the right thing to do, that alone counts as good will.

Arthur Schopenhauer by Johann Schäffer via Wikimedia Commons. This work is in the public domain.

Schopenhauer was a critic of Kant’s philosophy, including his ethics, and he objected that Kant’s view of the good will is “directly opposed to the genuine spirit of virtue; not the deed, but the willingness to do it, the love from which it results, and without which it is a dead work, this constitutes its meritorious element” ([1818] 1969, 526). Schopenhauer thought that good people are good because they want to do good actions and they feel love and compassion towards others. If we return to the example of working in the soup kitchen, if the person is showing up to the soup kitchen because he likes helping people or he feels compassion for the people he helps and wants to improve their lot, Schopenhauer would say this is a good person and thus a virtuous action.

Kant defended his position on good will by saying that an action done out of love or out of compassion is not fully autonomous. Autonomy means self-rule, and Kant saw it as a necessary condition for freedom and morality. If an action is not done autonomously, it is not really morally good or bad. Again, if our friend at the soup kitchen is working there because of some implant in his brain by which another person is able to control his every action, then the action is neither autonomous nor morally commendable.

Concerning acting out of love and compassion, Kant believed that when people act due to their emotions, then their emotions are in control, not their rationality. To be truly autonomous, for Kant, an action must be done because of reason. An action done because of emotion is not fully free and not quite fully moral. This doesn’t mean you shouldn’t enjoy doing good things. It just means that this shouldn’t be the reason underlying the action. According to Kant’s ethics, it’s morally commendable for a person, acting out of good will, to decide that helping at the soup kitchen is the right thing to do, to go there, and then to thoroughly enjoy doing so and feel great compassion for the people helped. The important point is that reason you do an action should be because you have determined that it is the right thing to do.

The Second Formulation of the Categorical Imperative

The idea underlying the second formulation is that all humans are intrinsically valuable. As Kant writes, “What has a price can be replaced by something else as its equivalent; what on the other hand is raised above all price and therefore admits of no equivalent has a dignity” (Groundwork 4.434). What has a price is a thing, but a person has dignity and is thus beyond price and irreplaceable. It follows that a person with dignity deserves respect and shouldn’t be treated as a thing.

Kant expresses this idea in the second formulation of his categorical imperative: “So act that you use humanity, whether in your own person or in the person of any other, always at the same time as an end, never merely as a means” (Groundwork 4:429).

That is, we shouldn’t treat people merely as means to ends; we should treat them as ends, including ourselves. To treat someone merely as a means is to not give the person the proper respect—to fail to treat the person with dignity, to treat the person as a thing. It makes sense to use inanimate objects as tools—you can use a hammer as a means to drive in nails without worrying about what the hammer feels about this because it’s a thing. But if you use a person in such a way, it devalues the person. Similarly, if you harm someone, take advantage of someone, or steal from someone, then you treat that person as a thing, as a means to your ends. Conversely, if you treat someone as having unlimited value, if you treat the person with dignity and respect, then you treat the person as an end.

One important thing to add is that Kant says we should never treat people “merely as a means.” The “merely” is there to acknowledge that we can treat people as means, so long as we don’t only treat them as means. It’s not unusual to have to use other people for their skills or knowledge, so it’s necessary to sometimes treat people as means. For example, imagine that your pipes need fixing, and you call a plumber. You’re using the plumber as a means because he is making your end (to fix your pipes) his end, but there is nothing wrong with this if you also treat him as an end—that is, if you are respectful and pay him appropriately. The plumber’s end is to make a living with his plumbing skills. By paying him the agreed-upon amount, you are making his end (earning a living) your end. Thus, in this situation, you both are effectively advancing each others’ ends at the same time and thus treating each other both as ends and means.

One way to think of the idea of treating someone as ends and means is that, when you treat people as ends, you make their ends your ends, and when you treat people as means, you force them to make their ends your ends. To explain, let’s look at an example from the first formulation. Since the first formulation and the second formulation of the categorical imperative are supposed to be saying the same thing, they should come to exactly the same conclusions about what’s right and wrong. Thus, since we discovered earlier that it’s wrong to make a false promise, then the second formulation should also tell us that false promises are wrong. In our example, you made the false promise because you needed to borrow money to pay off debts; thus, your end was to pay off debts, and by lying to your friend, you are forcing him to make your end (paying off debts) his end. If you told your friend that you needed money and might not be able to pay it back, your friend would be able to decide. He might decide to make your end his end (to pay off your debts for you), but by depriving him of that choice, you are treating him as an object. For similar reasons, we can also conclude that any time we deceive someone, we are treating the person as a mere means to our ends.

We can also look at the other example from the first formulation discussed above and see that it leads to the same conclusion. Kant argued that we have an obligation to sometimes help out others in need. To help people out is to make their ends our ends. For example, if you see that someone is poor and hungry, his end at that point might be to get food. If you give him food or money to buy food, you are making it your end to feed him. Since you should treat people as ends, then that means you should sometimes provide people with help.

In addition, the second formulation also includes the idea that we shouldn’t treat ourselves as mere means to ends. In the Groundwork, Kant gives two examples of duties to oneself: we shouldn’t commit suicide, and we should cultivate some of our useful talents. In the Metaphysics of Morals, Kant presents several more, including that you should not pursue greedy avarice, stupefy yourself with excessive food or drink, nor be excessively servile.

On the Morality of Suicide

The question of the morality of suicide was a heated topic of debate in the Western intellectual tradition in Kant’s day. Though we nowadays tend to think of suicide as a mental health issue and thus as a medical concern, it used to be much more often considered a moral concern. Suicide was a punishable crime in England until 1961, and both attempted and successful suicide could lead to serious penalties, with similar laws in many other countries.

The immorality of suicide was espoused by several influential Christian thinkers. Augustine, in his City of God (Book I, ch. 20), declared that the commandment, “Thou shalt not kill,” included suicide. Thomas Aquinas, in his Summa Theologiae (II-II, Q. 64, A. 5), argued that (1) since our natural inclination is to try to stay alive and extend our life as long as possible, suicide is unnatural and therefore wrong, that (2) since our community benefits from our continued existence, then suicide harms the community, and that (3) since our life is not our own, being a gift from God, then committing suicide is a crime against God. Thus, suicide harms the self, society, and God. Dante in his Inferno (Canto XIII), placed those who had committed suicide in the Second Ring of the Seventh Circle of Hell, for those who commit violence against the self ([1320] 1995).

Such arguments were influential in Kant’s day. His own arguments in the Groundwork are that (1) since suicide is motivated by self-interestedness (by a desire to end the sorrows a person is experiencing) and since self-interestedness normally impels us to try to improve our life, then suicide is self-contradictory and thus wrong (4:422) and that (2) by committing suicide one is treating oneself merely as a means and not as an end (4:429). Also, in his Metaphysics of Morals, he argues that suicide effectively harms the morality in the world by destroying one’s capacity for morality within oneself (6:423).

There were other authors who disagreed. Much earlier, in Utopia, Thomas More argued that suicide should be permitted in cases when people suffer from unpleasant and incurable diseases ([1516] 2012). Arthur Schopenhauer took the view in On Suicide that suicide, though not a sensible choice in most cases, can’t be considered morally wrong because your life and person are the things that most clearly belong to you ([1851] 2015). Thus, you can dispose of them how you wish. David Hume, in his essay Of Suicide, published posthumously, targeted Aquinas’s arguments that suicide harms self, society, and God: (1) Sometimes suicide doesn’t harm the self, since in some cases, continuing to live is worse than death. (2) Suicide doesn’t harm society because, by depriving society of oneself, one is merely withdrawing benefit, not harming society (and if one is actually a burden on society, then one does society great benefit). And (3) one’s life must be one’s own, otherwise it wouldn’t make sense to praise people for risking their life for others ([1777] 1998).

Such a list of duties does raise the question, though, of what it means to treat oneself as a mere means. The idea that we could treat ourselves as a mere means seems somewhat implausible, and if we look at it the way we explained it before (to treat people as a mere means is to force them to make their ends our ends), then it doesn’t make sense. Our ends are our ends and can’t be anything other than our ends.

Perhaps, by treating oneself as a mere means, one is not treating oneself with respect—as a person with dignity and with unlimited value. We can see how this might apply to duties like not being too servile or not being too avaricious. By being excessively servile, you are debasing yourself, making yourself into a thing to be used by someone else. And with excessive greed, you are elevating the value of money over and above your own value.

Another way to think about it is that, by treating oneself as a mere means, one is not giving proper respect to the humanity within oneself. The second formulation specifically forbids treating the humanity in ourselves and in others as a mere means. Concerning our humanity, Kant means mostly our capacity for rational human thought. So, by treating oneself as a mere means, one is not giving proper value to this rational capacity. One can see this in the case of stupefying oneself with excessive drink. Excessive drunkenness and opium use—the two examples Kant specifically mentions in the Metaphysics of Morals—dull one’s thinking, and Kant describes them as turning a person into an animal, though he seems to concede that some level of moderate alcohol consumption or opium use might be permissible (6:427-6:428). Similarly, in the Metaphysics of Morals, his argument against suicide is that, “To annihilate the subject of morality in one’s own person is to root out the existence of morality itself from the world” (6:423). That is, by committing suicide, you destroy some of the morality in the world by destroying your capacity for morality.

Kant on Animal Rights

Kant defines what counts as a person in terms of their capacity for rationality. This means that any being not capable of rationality lacks dignity and thus we don’t have the same moral obligation to not treat them as mere means. One of the significant implications for this is how it affects our duties to nonhuman animals. Kant’s ideas would imply that we can treat such animals however we wish. In terms of animal rights, whether animals have any rights (for example the right not to be mistreated, harmed, or killed), Kant would say that since they are not rational, they have no rights.

Kant does argue that it’s wrong to treat animals cruelly. This duty is derived from a person’s duty to himself. As Kant writes in The Metaphysics of Morals: “With regard to the animate but non-rational part of creation, violent and cruel treatment of animals is far more intimately opposed to a human being’s duty to himself, and he has a duty to refrain from this; for it dulls his shared feelings of their suffering and so weakens and gradually uproots a natural predisposition that is very serviceable to morality in one’s relations with other people” (6:443). That is, he is saying that mistreating animals will dull one’s compassion towards other living beings and thus make one a less virtuous person.

He is clear that “the human being is authorized to kill animals quickly (without pain),” which indicates that killing animals for food, or even hunting them for sport, is permissible, so long as it is done humanely. However, he does partially disapprove of using animals for medical experiments: “agonizing physical experiments for the sake of mere speculation, when the end could be achieved without these, are to be abhorred.” This passage was probably directed at the then-common practice of animal vivisection, but his words would suggest that animal experiments for medical purposes, in cases when the goal is to save human lives, might perhaps be permissible. Though we should emphasize that this duty to not mistreat animals is only because of the harm one might do to oneself by this cruelty to animals: “it is always only a duty of the human being to himself” (6:443).

Problems with the Second Formulation

One of the main problems with the second formulation of the categorical imperative is that it’s somewhat vague. There are clear-cut cases of using people as mere means, such as slaveholders exploiting their slaves, but what about something more ambiguous like an employer underpaying his employees? The employer is advancing the employees’ ends by paying them, but clearly would better promote their ends if wages were raised. But what exactly counts as “underpaying” is unavoidably vague, and the categorical imperative doesn’t give clear guidance.

Another problem is that it doesn’t seem that morality is entirely about not treating people as mere means to ends. The categorical imperative is supposed to be the sole principle of morality. Thus, we should be able to derive all moral duties from it. But it seems like there are actions that are morally wrong but which don’t amount to treating anyone as mere means. For example, the destruction of the natural world through carelessness or negligence seems wrong. If I accidentally start a forest fire by setting off fireworks when there is high fire risk, aren’t I morally culpable? But in what way have I treated a person merely as a means? The forest is not rational and thus is not an object of direct moral consideration. Kant does write, “A propensity to wanton destruction of what is beautiful in inanimate nature is opposed to a human being’s duty to himself” (6:443). But if it’s through neglect, it doesn’t appear to be treating any person merely as means. Similarly, what about our obligation to care for the dead? If my mother wanted to be given a Christian burial and instead I simply left her body out in the woods, that would seem to be quite immoral. But how would we explain that in terms of treating her as a mere means? The body is no longer a person; it lacks humanity, rationality, and thus is a thing, and it’s permissible for us to treat things as means. There are perhaps ways a defender of Kant could explain why these are wrong within a Kantian framework, but it is a potential limitation of the theory.

Kant is only able to derive obligations to not mistreat physical objects and non-rational living things from obligations to oneself and other rational beings. By misusing objects and animals, we habituate ourselves to not giving others the proper respect, which thereby debases our character. But it does seem strange to say that the reason why it’s wrong to damage non-human life is because it’s harmful to oneself.

The Third Formulation of the Categorical Imperative

Kant gives a third formulation of the categorical imperative based on the notion of a kingdom of ends. By kingdom, Kant explains, “I understand a systematic union of various rational beings through common laws” (Groundwork 4:433). By a kingdom of ends we’re to imagine an interconnected world of rational beings where everyone is treated as an end and treats everyone else as ends and everyone shares the same set of laws.

Kant explains the third formulation as, “act in accordance with the maxims of a member giving universal laws for a merely possible kingdom of ends” (Groundwork 4:439).

As mentioned, Kant believes that autonomy is necessary for morality. Kant is here emphasizing that we are each the creators of our own moral rules. We are fully autonomous beings, and if our morals were imposed on us, then that would undermine our autonomy; we would no longer fully decide our actions. To maintain full autonomy, everyone must be the creator of their own moral rules.

However, if everyone is creating their own moral rules, then wouldn’t people disagree on what is right and wrong? Kant doesn’t believe so. He believes that the categorical imperative is the only rational moral rule, and he also believes that we can derive a complete, consistent set of moral duties from the categorical imperative. Thus, every person who is fully following their rationality will agree on what is right and wrong.


Despite many of the criticisms to which Kant’s ethics has been subject, it remains one of the most influential ethical theories in contemporary Western ethics. Many thinkers agree with its emphasis on ethics being fundamentally rational and being justifiable through reason. The first and second formulations of the categorical imperative also do have great intuitive appeal. Despite the abstract way that the first formulation is expressed, its core meaning is that ethical rules should be universal and that if any rule can’t be universalized, it shouldn’t be followed. This appeals to our sense that all people deserve equal moral consideration and we shouldn’t make special exceptions for ourselves or others. And the second formulation speaks to the idea that we are beings with intrinsic value and with dignity, and to use people as if they are objects or tools is deeply immoral. Kant has put these intuitions into a sophisticated and carefully thought out framework that remains, to this day, a very useful way of thinking about difficult moral questions.


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Aquinas, Thomas. 1920. The Summa Theologiæ, 2nd ed., trans. Fathers of the English Dominican Province. http://www.newadvent.org/summa/

Augustine. (426) 1887. The City of God, trans. Marcus Dods. In Nicene and Post-Nicene Fathers 1(2), ed. Philip Schaff. Grand Rapids, MI: W. M. B. Eerdmans Publishing Company. http://www.ccel.org/ccel/schaff/npnf102.i.html

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Hume, David. (1777) 1998. Of Suicide. In Dialogues Concerning Natural Religion and the Posthumous Essays, ed. Richard H. Popkin. Indianapolis, IN : Hackett Publishing Company.

Kant, Immanuel. (1797). The Metaphysics of Morals. In Practical Philosophy, 353-603.

Kant, Immanuel. (1785). Groundwork of the Metaphysics of Morals. In Practical Philosophy, 37-108.

Kant, Immanuel. (1797). “On a Supposed Right to Lie From Philanthropy.” In Practical Philosophy, 605-615.

More, Thomas. Utopia. (1516) 2012. In Open Utopia, ed. Stephen Duncombe. Wivenhoe/New York/Port Watson: Minor Compositions. http://theopenutopia.org

Schopenhauer, Arthur. (1818) 1969. The World as Will and Representation, Vol. 1., trans. E. F. J. Payne. New York, NY: Dover Publications.

Schopenhauer, Arthur. (1851) 2015. On Suicide. In Parerga and Paralipomena: Short Philosophical Essays, Vol. 2, eds. Adrian Del Caro and Christopher Janaway. Cambridge: Cambridge University Press.

  1. There are many different editions and translations of Kant’s works, and it is common practice in the philosophical community to use a standard referencing system that is the same across all of these rather than using page numbers (which differ across the various editions). The standard system, used in this chapter as well, refers to the German Royal Academy of Sciences edition of Kant’s works, Kant’s Gesammelte Schriften. Most editions of Kant’s texts will have the Academy reference numbers in them to make it easy to find quotes and arguments across editions.


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