3.4.2 Deontological Ethics


By the end of this section you will discover:

  • The meaning of Deontological Ethics.
  • Immanuel Kant’s approach to Ethics.
  • Key concepts in Kant’s ethics, including:
    • Duty
    • The Good Will
    • The Categorical Imperative
  • Several important formulations of Kant’s Categorical Imperative.
  • Suicide as an example of Kantian thinking.
  • Strengths and Weaknesses of Kantian Ethics.


In Normative Ethics Deontological theories are those that maintain that ethical evaluations are rooted somehow in the action or some feature of the action which would result in a moral duty or obligation. In this approach, the consequences of the action are not generally considered to be morally relevant.  Thus, deontological theories often are based on or generate a set of duties. Deon is Greek for duty or obligation.  What is the source of such duty?  Various theories answer that question differently.  It could be a deity, natural law, reason, a sense of justice, or one’s sense of self. (Sullivan and Pecarino, Ch. 7)

Immanuel Kant: The Moral Imperative

Engraving depicting Emanuel Kant
Immanuel Kant (1724- 1804) from an engraving in the German National Library.

Immanuel Kant was born in 1724 in Konigsberg in East Prussia, where he died in 1804. Kant is famous for revolutionizing how we think about just about every aspect of the world — including science, art, ethics, religion, the self, and reality. He is one of the most important thinkers of all time, which is even more remarkable given the fact that Kant is a truly awful writer. His sentences are full of technical language, are very long, and incredibly dense. You have been warned!

Kant is a rationalist writing during the Enlightenment (1685–1815). He thinks that we can gain knowledge from our senses and through our rational capacities. This means his general philosophical approach starts by asking what we can know a priori. This is key to understanding his work but also makes his writing on ethics seem a bit odd. We think the study of ethics — unlike say math — ought to direct our eye to what is going on around us in the world. Yet Kant starts by turning his eyes “inward” to thinking about ethical ideas.

Kant believes that in doing this people will come to recognize that certain actions are right and wrong irrespective of how we might feel and irrespective of any consequences. For Kant, actions are right if they respect what he calls the Categorical Imperative. For example, because lying fails to respect the Categorical Imperative it is wrong and is wrong irrespective of how we might feel about lying or what might happen if we did lie; it is actions that are right and wrong rather than consequences. This means that Kant’s theory is deontological rather than teleological. It focuses on our duties rather than our ends/goals/consequences.

There is, however, something intuitive about the idea that morality is based on reason rather than feelings or consequences. Consider my pet cat Spartan. He performs certain actions like scrabbling under bed covers, meowing at birds, and chasing his tail. Now consider my daughter Beth, she performs certain actions like caring for her sister and helping the homeless.

Spartan’s actions are not moral whereas Beth’s actions are. Spartan’s thinking and actions are driven by his desires and inclination. He eats and plays and sleeps when he desires to do so, there is no reasoning on his part. Beth, in contrast, can reflect on the various reasons she has, reasons to care for her sister and the homeless.

We might think then that humans are moral beings not because we have certain desires but precisely because we are rational. We have the ability to “stand back” and consider what we are doing and why. Kant certainly thought so and he takes this insight as his starting point.

Kant & Categorical Imperatives: Crash Course Philosophy #35

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Some Key Kantian Ideas

  • Duty

Kant’s main works in ethics are his Metaphysics of Morals (1797) and the Groundwork of the Metaphysics of Morals (1785). Neither gives practical advice about particular situations but rather through rational reflection, Kant seeks to establish the supreme principle of morality.

He starts with the notion of “duty” and although this is a rather old-fashioned term, the idea behind it should sound familiar. Imagine, your friend has told you that she is pregnant but asks you to promise to keep her secret. Through the coming weeks, this juicy bit of gossip is on the tip of your tongue, but you do not tell anyone because of your promise. There are things we recognize as being required of us irrespective of what we (really) desire to do. This is what Kant means by duty.

  • The Good Will

But this raises the question. If it is not our desires that move us to do what is right (even really strong desires), what does? In our example, why is it that we keep our promise despite the strong desire to gossip? Kant’s answer is “the good will.”  For Kant, the good will is something in us that desires to do what is right regardless of the effects or consequences:


A good will is good not because of what it effects or accomplishes – because of its fitness for attaining some proposed end: it is good through its willing alone – that is, good in itself.
It is also good without qualification.
It is impossible to conceive anything at all in the. world, or even out of it, which can be taken as good without qualification, except a good will.

What does Kant mean? Well, pick anything you like that you think might make an action good — for example, happiness, pleasure, courage, and then ask yourself if there are any situations you can think of where an action having those features makes those actions worse.

It seems there are. For example, imagine someone who is happy when kicking a cat; someone taking pleasure in torture; or a serial killer whose courage allows her to abduct children in broad daylight. In such cases, happiness, pleasure, and courage only serve to make the actions more evil. Kant thinks we can repeat this line of thinking for anything and everything, except one thing — the good will.

The good will unlike anything else is good unconditionally. and what makes a good will “good” is willing alone, not other attitudes, consequences, or characteristics of the agent. Even Kant thinks this sounds like a rather strange idea. So how can he (and we) be confident that the good will even exists?

Consider Mahatma Gandhi’s (1869–1948) non-violent protest for Indian independence. He stood peacefully whilst the British police beat him. Here is a case where there must have been an overwhelming desire to fight back. But he did not. In this type of action, Kant would claim that we “see” the good will “shining like a jewel.”  Seeing such resilience in the face of such awful violence, we are humbled and can recognize, what Kant calls, its moral worth.

Taking it to the streets…

Ask several friends to share a list of moral actions that are good without qualification, or without considering the consequences.

Test each friend’s responses by sharing them with the other friends and asking for their feedback. Do they agree with the choices? If not, what is wrong with one or more of them?

Obviously, not all actions are as significant as Gandhi’s. However, Kant thinks that any acts like this, which are performed despite conflicting desires, are due to the good will. Considering such actions means we can recognize that the good will exists.

  • Acting for the Sake of Duty and Acting in Accordance with Duty

From what we have said above about the nature of duty and good will, we can see why Kant says that to act from good will is acting for the sake of duty. We act despite our desires to do otherwise. For Kant, this means that acting for the sake of duty is the only way that an action can have moral worth. We will see below what we have to do for our actions to be carried out for the sake of duty. However, before we do this, we need to be really clear on this point about moral worth.

Imagine that you are walking with a friend. You pass someone begging on the street. Your friend starts to weep, fumbles in his wallet and gives the beggar some money, and tells you that he feels such empathy with the poor man that he just has to help him.

For Kant, your friend’s action has no moral worth because what is moving him to give money is empathy rather than duty! He is acting in accordance with duty. However, Kant does think your friend should be applauded as such an action is something that is of value although it wouldn’t be correct to call it a moral action.

To make this point clearer, Kant asks us to consider someone who has no sympathy for the suffering of others and no inclination to help them. But despite this:

…he nevertheless tears himself from his deadly insensibility and performs the action without any inclination at all, but solely from duty, then for the first time, his action has genuine moral worth.

In contrast to our friend, this person is acting for the sake of duty and hence their action is moral. We must be careful though. Kant is not telling us to become emotionally barren robots! He is not saying that before we can act morally we need to get rid of sympathy, empathy, desires, love, and inclinations. This would make Kant’s moral philosophy an absurd non-starter.

Let us see why Kant is not saying this. Consider an action such as giving to others. We should ask whether an action of giving to others would have been performed even if the agent lacked the desire to do so. If the answer is “yes” then the act has moral worth. This though is consistent with the agent actually having those desires. The question for Kant is not whether an agent has desires but what moved the agent to act. If they acted because of those desires, they acted in accordance with duty and their action had no moral worth. If they acted for the sake of duty, and just happened to have those desires, then their action has moral worth.

  • Categorical and Hypothetical Imperatives

If we agree with Kant and want to act for the sake of duty, what should we do? His answer is that we have to act out of respect for the moral law. He has two examples of how this works in practice: lying and suicide. We look at the former in Chapter 13, we will consider Kant’s example of suicide at the end of this chapter. However, before doing this we need to get a sense of what Kant has in mind when he talks about acting out of respect for the moral law.

The moral law is what he calls the “Categorical Imperative”. He thinks there are three formulations of this.




First Formulation


…act only according to that maxim through which you can at the same time will that it become a universal law.

Second Formulation


So act that you use humanity, in your own person as well as in the person of any other, always at the same time as an end, never merely as a means.

Third Formulation


…every rational being must so act as if he were through his maxim always a lawmaking member in the universal kingdom of ends.

We will consider these in turn, showing how they are linked. Consider then, CI-1. Kant’s idea is that we use this “test” to see what maxims are morally permissible. If we act in accordance with those then we are acting from duty and our actions have moral worth. Let us look at what this means.

Initially, it is worth considering what “categorical” and “imperative” mean. An imperative is just a command. “Clean your room!” is an imperative I give my daughter every Saturday. “Do not park in front of these gates!” is a command on my neighbor’s gate. “Love your God with all your heart, mind and soul” is a command from the Bible.

What about the “categorical” part? If a command is categorical then people ought to follow it irrespective of how they feel about following it, irrespective of what consequences might follow, or who may or may not have told them to follow it. For example, the command “do not peel the skin of babies” is categorical. You ought not to do this and the fact that this might be your life’s ambition, or that you really want to do it, or that your teacher has told you to do it, is completely irrelevant.

Contrast this with Hypothetical Imperatives. If I tell my daughter to clean her room, this is hypothetical. This is because whether she ought to clean her room is dependent on conditions about her and me. If she does not care about a clean room and about what her dad thinks, then it is not true that she ought to clean her room. Most commands are hypothetical. For example, “study!” You ought to study only if certain things are true about you; for example, that you care about doing well, that you want to succeed in the test etc.

Kant thinks that moral “oughts” — for example, “you ought not to lie” — are categorical. They apply to people irrespective of how they feel about them.

The next thing we need is the idea of a “maxim”. This is relatively simple and is best seen through the following examples. Imagine I’m considering whether to make a false promise. Perhaps I think that by falsely promising you that l will pay you back I will be more likely to get a loan from you. In that case, my maxim is something like “whenever I can benefit from making a false promise I should do so”.

Imagine I decide to exercise because I feel depressed, then I may be said to be acting on the maxim “Whenever I feel depressed, I will exercise”. A maxim is a general principle or rule upon which we act. We do not decide on a set of maxims, perhaps writing them down, and then try to live by them but rather a maxim is the principle or rule that can make sense of an action whether or not we have thought about it in these terms.

The First Formulation of the Categorical Imperative

Let’s put these bits together in relation to CI-1:

… act only according to that maxim through which you can at the same time will that it become a universal law.


The “test” that CI-1 prescribes is the following. Consider the maxim on which you are thinking about acting and ask whether you can either (a) conceive that it becomes a universal law, or (b) will that it become a universal law. If a maxim fails on either (a) or (b) then there is no good reason for you to act on that maxim and it is morally impermissible to do so. If it passes the CI test, then it is morally permissible.

Kant is not saying that the CI-1 test is a way of working out what is and what is not moral. Presumably, we can think of lots of maxims, which are non-moral, which pass the test, for example, “whenever I am bored, I will watch TV”.

Equally, he is not saying that if a maxim cannot be universalized then it is morally impermissible. Some maxims are just mathematically impossible. For example, “whenever I am going to exercise, I will do it for an above the average amount of time”. This maxim cannot be universalized because we cannot conceive that everyone does something above “average.

Finally, it is worth remembering that the maxim must be able to be willed as a universal law. This is important because maxims such as “if your name is Jill and you are 5 ft 11, you can lie” will fail to be universalized because you cannot will that your name is Jill or that your height is 5 ft 11. It has to be possible to will as a universal law and for this to be true it must be at least possible for it actually to come about. This shows that the common concern that we can get any maxim to pass the CI-1 test by simply adding more and more specific details, such as names, heights, or locations, fails. This is very abstract. Let us consider an example.

  • Perfect and Imperfect Duties

Recall the example of making a false promise to secure a loan. The maxim is “whenever I can benefit from doing so, I should make a false promise”. The question is whether I could conceive or will that this becomes a universal law.

I could not. If everyone followed this maxim then we would all believe everyone else could make a false promise if it would benefit them to do so. Kant thinks such a situation is not conceivable because the very idea of making a promise relies on trust. But if “whenever it is of benefit to you, you can make false promises” was to become a universal law then there would be no trust and hence no promising. So, by simply thinking about the idea of promising and lying we see the maxim will fail the test and because we cannot universalize the maxim, then making a false promise becomes morally impermissible. This is true universally for all people in all circumstances for anyone can, in principle, go through the same line of reasoning.

A maxim failing at (a) is what Kant calls a contradiction in conception, and failing at (a) means we are dealing with what Kant calls a perfect duty. In our example, we have shown we have a perfect duty not to make false promises.

Consider another example. Imagine that someone in need asks us for money but we decide not to help them. In this case, our maxim is “whenever someone is in need and asks for money do not give them money”. Does this pass the CI-1 test?

No, it fails the CI-1 test. Although it is true that the maxim passes (a) not giving to the needy does not threaten the very idea of giving money away. Kant thinks that anyone thinking about this will see that that maxim will fail at (b) and hence it is morally impermissible. Here is why.

You cannot know if you will be in need in the future and presumably you would want to be helped if you were in need. In which case you are being inconsistent if you willed that “people should not help those in need” should become a universal law. For you might want people to help those in need in the future, namely, you.

So, we cannot will the maxim “whenever someone is in need do not help them” to become a universal moral law. Again, this is a thought process that anyone can go through, and it means that this moral claim is true universally for all people in all circumstances. Failing at (b) is what Kant calls a contradiction in will, and failing at (b) means we are dealing with what Kant calls an imperfect duty.

Ponder if you will…

Can it ever be moral from Kant’s point of view for lawmakers to create laws from which they are exempt? For instance, can a moral maxim ever state, “Everyone with blonde hair must pay twice the tax of any other citizen unless that person is a member of the Senate–that person is exempt from all taxes?”

Could a person reasonably “will” that this would be true?

It is absolutely key to recognize that CI-1 is not simply asking “what if everyone did that?” CI-1 is not a form of Utilitarianism. Kant is not saying that it is wrong to make false promises because if people did then the world would be a horrible place. Rather Kant is asking whether we can conceive or will the maxim become a universal law.

Second Formulation of the Categorical Imperative

The second formulation (CI-2) is the following:

So act that you use humanity, in your own person as well as in the person of any other, always at the same time as an end, never merely as a means.

Kant thinks that CI-1 and CI-2 are two sides of the same coin, though precisely how they are related is a matter of scholarly debate. Put very simply CI-2 says you should not use people because if you do, you are failing to treat them as rational agents, and this is morally wrong.

For example, if I use your essay without your knowledge then I have not treated you as a rational agent like I would have done had I asked you for your essay and you had freely chosen to let me have it. But given that I did not ask you, I was, in a sense, making choices on your behalf and thus did not treat you as a rational agent. So according to Kant, I should always treat you as an end, never as a means. I should always treat you as a free rational agent.

Taking it to the streets…

Ask a few friends the question “Is it ever right to use another person without their consent?”

What kinds of answers do they offer?

If they say no, can you suggest to them times when indeed it might be?

For example, people convicted of crimes do not give consent to be imprisoned, yet society puts them there anyway. Or, more benignly, someone might tell a white lie so as not to hurt another person’s feelings.

What would Kant say about these choices?

Kant’s theory then has a way of respecting the dignity of people. We should treat people with respect and with dignity purely on the basis that they are rational agents, and not because of their race, gender, education, upbringing, etc. From this, you can also see that Kant’s theory allows us to speak about “rights”. If someone has a right then they have this right irrespective of gender, education, upbringing, etc. For example, Jill has a right to free speech because she is a person, consequently that right will not disappear if she changes her location, personal circumstances, relationship status, political viewpoint, etc. After all, she does not stop being a person.

Importantly, CI-2 does not say that you either treat someone as a means or an end. I could treat someone as an end by treating them as a means. Suppose that you have freely decided to become a taxi driver. If I use you as a means by asking you to take me to the airport, I am also treating you as an end. But Kant does not believe this to be morally wrong because I am respecting you as a rational agent; after all, you chose to be a taxi driver. Of course, if I get into your car and point a gun at your head and ask to be taken to the airport then I am not treating you as an end but rather solely as a means, which is wrong.

The Third Formulation of the Categorical Imperative

The final formulation of the Categorical Imperative is a combination of CI-1 and CI-2. It asks us to imagine a kingdom that consists of only those people who act on CI-1. They never act on a maxim that cannot become a universal law. In such a kingdom people would treat people as ends

… every rational being must so act as if he were through his maxim always a lawmaking member in the universal kingdom of ends.

In summary, we have seen that Kant thinks that acts have moral worth only if they are carried out for the sake of duty. Agents act for the sake of duty if they act out of respect for the moral law, which they do by following the Categorical Imperative in one of its formulations.

Consequently, Kant thinks that acts are wrong and right universally, irrespective of consequences and desires. If lying is wrong, then it is wrong in all instances. From all this, it follows that we cannot be taught a set of moral rules for each and every situation, and Kant believes that it is up to us to work it out for ourselves by thinking rationally.

There have been, and continue to be, many books and journal articles written about Kant’s ethics. He has a profound and deep insight into the nature of morality, and he raises some fundamental questions about what it is to be human. Kant’s moral theory is radically Egalitarian as his theory is blind to individual personal circumstances, race, gender, and ethnicity. Everyone is equal before the moral law!

Related to this, his theory respects the rights of individuals and, relatedly, their dignity. Any theory that is to have a hope of capturing our notion of rights needs to be able to respect the thought that a right is not something that disappears if circumstances change. Jill has a right to life, period; we do not say Jill has a right to life “if…” and then have to fill in the blanks. This is precisely something that Kant’s theory can give us. CI-1 generates maxims that do not have exceptions and CI-2 tells us that we should always treat everyone as an end in themselves and never solely as a means to an end. It tells us, for example, that we ought not to kill Jill, and this holds true in all circumstances.

There are, though, a number of tough questions that Kant’s work raises. We consider some of these below. However, as with all the philosophical ideas we discuss in this book, Kant’s work is still very much alive and has defenders across the world. Before we turn to these worries, we work through an example that Kant gives regarding suicide.

An example of Kantian Ethical Reasoning: Suicide

Kant is notoriously stingy with examples. One he does mention is suicide. This is an emotional topic and linked to questions about mental health and religion. An attraction of Kant’s view is the ability to apply his Categorical Imperatives in a dispassionate way. His framework should allow us to “plug in” the issue and “get out” an answer. Let’s see how this might work.

Kant thinks that suicide is always wrong and has very harsh words for someone who attempts suicide

He who so behaves, who has no respect for human nature and makes a thing of himself, becomes for everyone an Object of free will. We are free to treat him as a beast, as a thing, and to use him for our sport as we do a horse or a dog, for he is no longer a human being; he has made a thing of himself, and, having himself discarded his humanity, he cannot expect that others should respect humanity in him.

But why does he think this? How does this fit with Kant’s Categorical Imperatives? We will look at the first two formulations.

Fundamental to remember is that for Kant the motive that drives all suicide is “avoid evil”. By which he means avoiding suffering, pain, and other negative outcomes in one’s life. All suicide attempts are due to the fact that we love ourselves and thus want to “avoid evils” that may befall us.

Imagine then that I decide to commit suicide. Given what we have just said about my motives this means I will be acting on this maxim: “From self‐love, I make as my principle to shorten my life when its continued duration threatens more evil than it promises satisfaction”.

Following CI-1 the question then is whether it is possible to universalize this maxim. Kant thinks not. For him, it is unclear how we could will it that all rational agents as the result of self-love can destroy themselves when their continued existence threatens more evil than it promises satisfaction. For Kant self-love leading to the destruction of the self is a contradiction. Thus, he thinks that we have a perfect (rather than an imperfect) duty to ourselves not to commit suicide. To do so is morally wrong. This is how Kant puts it:

One sees at once a contradiction in a system of nature whose law would destroy life [suicide] by means of the very same feeling that acts so as to stimulate the furtherance of life [self-love], and hence there could be no existence as a system of nature. Therefore, such a maxim cannot possibly hold as a universal law of nature and is, consequently, wholly opposed to the supreme principle of all duty.

Notice a few odd things here in relation to CI-1. The point about universalization seems irrelevant. Kant could have just said it is a contradiction to will from self-love the destruction of oneself. It seems that there is nothing added by asking us to consider this point universalized. It does not add weight to the claim that it is a contradiction.

Second, it is not really a “contradiction” at all! It is different from the lying promise example. In this, it seems that the very concept of a promise relies on trust, which lying would destroy. In contrast in the suicide case, the “contradiction” seems more like a by-product of Kant’s assumption regarding the motivation of suicidal people. So, we can avoid the “contradiction” if we allow for the possibility that suicide need not be driven by self-love. If this were true, then there would be no “contradiction”. Hence, it seems wrong to call the duty not to kill oneself — if such a duty exists — a “perfect” duty. So, the first formulation does not give Kant the conclusion that suicide is morally wrong.

Moving to the second formulation. This helps us understand Kant’s harsh assessment of people attempting suicide. Remember he calls such people “objects” or “beasts” or “things”. So, what is the difference between beasts or objects or things, and humans? The answer is that we are rational. Recall, that for Kant our rationality is of fundamental value. If anyone’s actions do not recognize someone else’s rationality, then they have done something morally wrong. This amounts to treating them merely as means to our own end. Given all this, you can see what Kant is getting at. For him committing suicide is treating yourself as a mere means to some end — namely the end of avoiding pain and suffering etc. — and not an end in itself. You are treating yourself as a “beast” a “thing” an “object”, not as a human being with the gift of reason. This is morally wrong.

Moreover, if you do this, then others treating you with respect as a rational person can conclude that you also want others to treat you in this way. Because if you are rational then you must think that it is OK to universalize the maxim that we can treat others as objects, beasts, and things. They can thus treat you as a beast, object, and thing and still be treating you with respect as a rational agent. With regard to attempting suicide, your action is wrong because you have ignored your own rationality. You have treated yourself as a mere means to an end.

But, like the first formulation, this is very weak. It is unclear why in attempting suicide you are treating yourself as a mere means to an end. You might think you are respecting your rationality by considering suicide. Recall that Kant says that it is sometimes fine to treat people as a means to an end, e.g., a taxi driver. It is fine when people have given consent for you to treat them that way. In that case, suicide might be like the taxi driver’s case. We have freely decided to treat ourselves as a means to an end. We are, then, treating ourselves as rational agents and not doing something morally wrong by committing suicide.

There are some other things that Kant says about the wrongness of suicide that do not link to the Categorical Imperatives. For example, he talks about humans being the property of God and hence our lives not being something we can choose to extinguish. However, we need not discuss this here.

There is a consensus among Kantian scholars that, as it stands, Kant’s argument against suicide fails. There are some though who use Kant’s ideas as a starting point for a more convincing argument against suicide.

Excerpts from Kant’s Groundwork of the Metaphysics of Morals

Groundwork of the Metaphysics of Morals (1785; German: Grundlegung zur Metaphysik der Sitten) is the first of Immanuel Kant’s mature works on moral philosophy. In the following selections, see if you can find:

What does Kant suggest is a characteristic unique to rational beings?

Everything in nature works according to laws. Rational beings alone have the faculty of acting according to the conception of laws, that is according to principles, i.e., have a will. Since the deduction of actions from principles requires reason, the will is nothing but practical reason. If reason infallibly determines the will, then the actions of such a being which are recognized as objectively necessary are subjectively necessary also, i.e., the will is a faculty to choose that only which reason independent of inclination recognizes as practically necessary, i.e., as good. But if reason of itself does not sufficiently determine the will, if the latter is subject also to subjective conditions (particular impulses) which do not always coincide with the objective conditions; in a word, if the will does not in itself completely accord with reason (which is actually the case with men), then the actions which objectively are recognized as necessary are subjectively contingent, and the determination of such a will according to objective laws is obligation, that is to say, the relation of the objective laws to a will that is not thoroughly good is conceived as the determination of the will of a rational being by principles of reason, but which the will from its nature does not of necessity follow.

What does Kant mean by an “imperative”?

The conception of an objective principle, in so far as it is obligatory for a will, is called a command (of reason), and the formula of the command is called an Imperative.

All imperatives are expressed by the word ought [or shall], and thereby indicate the relation of an objective law of reason to a will, which from its subjective constitution is not necessarily determined by it (an obligation). They say that something would be good to do or to forbear, but they say it to a will which does not always do a thing because it is conceived to be good to do it. That is practically good, however, which determines the will by means of the conceptions of reason, and consequently not from subjective causes, but objectively, that is on principles which are valid for every rational being as such. It is distinguished from the pleasant, as that which influences the will only by means of sensation from merely subjective causes, valid only for the sense of this or that one, and not as a principle of reason, which holds for everyone. …

What are the two kinds of Imperatives? How do they differ?

Now all imperatives command either hypothetically or categorically. The former represent the practical necessity of a possible action as means to something else that is willed (or at least which one might possibly will). The categorical imperative would be that which represented an action as necessary of itself without reference to another end, i.e., as objectively necessary.

Since every practical law represents a possible action as good and, on this account, for a subject who is practically determinable by reason, necessary, all imperatives are formulae determining an action which is necessary according to the principle of a will good in some respects. If now the action is good only as a means to something else, then the imperative is hypothetical; if it is conceived as good in itself and consequently as being necessarily the principle of a will which of itself conforms to reason, then it is categorical….

Accordingly, the hypothetical imperative only says that the action is good for some purpose, possible or actual. …. [while] the categorical imperative declares an action to be objectively necessary in itself without reference to any purpose….

And thus the imperative which refers to the choice of means to one’s own happiness, i.e., the precept of prudence, is still always hypothetical; the action is not commanded absolutely, but only as means to another purpose.

Finally, there is an imperative which commands a certain conduct immediately, without having as its condition any other purpose to be attained by it. This imperative is Categorical. It concerns not the matter of the action, or its intended result, but its form and the principle of which it is itself a result; and what is essentially good in it consists in the mental disposition, let the consequence be what it may. This imperative may be called that of Morality….

Which kind of imperative is appropriate for a moral law?

We shall therefore have to investigate à priori the possibility of a categorical imperative, as we have not in this case the advantage of its reality being given in experience, so that [the elucidation of] its possibility should be requisite only for its explanation, not for its establishment. In the meantime it may be discerned beforehand that the categorical imperative alone has the purport of a practical Law: all the rest may indeed be called principles of the will but not laws, since whatever is only necessary for the attainment of some arbitrary purpose may be considered as in itself contingent, and we can at any time be free from the precept if we give up the purpose; on the contrary, the unconditional command leaves the will no liberty to choose the opposite; consequently it alone carries with it that necessity which we require in a law….

When I conceive a hypothetical imperative, in general I do not know beforehand what it will contain until I am given the condition. But when I conceive a categorical imperative, I know at once what it contains. For as the imperative contains besides the law only the necessity that the maxims shall conform to this law, while the law contains no conditions restricting it, there remains nothing but the general statement that the maxim of the action should conform to a universal law, and it is this conformity alone that the imperative properly represents as necessary.

What is Kant’s first formulation of the Categorial Imperative?

There is therefore but one categorical imperative, namely, this: Act only on that maxim whereby thou canst at the same time will that it should become a universal law.

Now if all imperatives of duty can be deduced from this one imperative as from their principle, then, although it should remain undecided what is called duty is not merely a vain notion, yet at least we shall be able to show what we understand by it and what this notion means.

Since the universality of the law according to which effects are produced constitutes what is properly called nature in the most general sense (as to form), that is the existence of things so far as it is determined by general laws, the imperative of duty may be expressed thus: Act as if the maxim of thy action were to become by thy will a Universal Law of Nature.

We will now enumerate a few duties, adopting the usual division of them into duties to ourselves and ourselves and to others, and into perfect and imperfect duties.

In these four examples, how does Kant say we should employ the Categorical Imperative?

A man reduced to despair by a series of misfortunes feels wearied of life but is still so far in possession of his reason that he can ask himself whether it would not be contrary to his duty to himself to take his own life. Now he inquires whether the maxim of his action could become a universal law of nature. His maxim is: “From self-love I adopt it as a principle to shorten my life when its longer duration is likely to bring more evil than satisfaction.” It is asked then simply whether this principle founded on self-love can become a universal law of nature. Now we see at once that a system of nature of which it should be a law to destroy life by means of the very feeling whose special nature it is to impel to the improvement of life would contradict itself and, therefore, could not exist as a system of nature; hence that maxim cannot possibly exist as a universal law of nature and, consequently, would be wholly inconsistent with the supreme principle of all duty.

Another finds himself forced by necessity to borrow money. He knows that he will not be able to repay it but sees also that nothing will be lent to him unless he promises stoutly to repay it in a definite time. He desires to make this promise, but he has still so much conscience as to ask himself: “Is it not unlawful and inconsistent with duty to get out of a difficulty in this way?” Suppose however that he resolves to do so: then the maxim of his action would be expressed thus: “When I think myself in want of money, I will borrow money and promise to repay it, although I know that I never can do so.” Now this principle of self-love or of one’s own advantage may perhaps be consistent with my whole future welfare; but the question now is, “Is it right?” I change then the suggestion of self-love into a universal law, and state the question thus: “How would it be if my maxim were a universal law?” Then I see at once that it could never hold as a universal law of nature but would necessarily contradict itself. For supposing it to be a universal law that everyone when he thinks himself in a difficulty should be able to promise whatever he pleases, with the purpose of not keeping his promise, the promise itself would become impossible, as well as the end that one might have in view in it, since no one would consider that anything was promised to him but would ridicule all such statements as vain pretenses.

A third finds in himself a talent which with the help of some culture might make him a useful man in many respects. But he finds himself in comfortable circumstances and prefers to indulge in pleasure rather than to take pains in enlarging and improving his happy natural capacities. He asks, however, whether his maxim of neglect of his natural gifts, besides agreeing with his inclination to indulgence, agrees also with what is called duty. He sees then that a system of nature could indeed subsist with such a universal law although men (like the South Sea islanders) should let their talents rest and resolve to devote their lives merely to idleness, amusement, and propagation of their species- in a word, to enjoyment; but he cannot possibly will that this should be a universal law of nature or be implanted in us as such by a natural instinct. For, as a rational being, he necessarily wills that his faculties be developed, since they serve him and have been given him, for all sorts of possible purposes.

A fourth, who is in prosperity, while he sees that others have to contend with great wretchedness and that he could help them, thinks: “What concern is it of mine? Let everyone be as happy as Heaven pleases, or as he can make himself; I will take nothing from him nor even envy him, only I do not wish to contribute anything to his welfare or to his assistance in distress!” Now, no doubt if such a mode of thinking were a universal law, the human race might very well subsist and doubtless even better than in a state in which everyone talks of sympathy and goodwill, or even takes care occasionally to put it into practice, but, on the other side, also cheats when he can, betrays the rights of men, or otherwise violates them. But although it is possible that a universal law of nature might exist in accordance with that maxim, it is impossible to will that such a principle should have the universal validity of a law of nature. For a will which resolved this would contradict itself, inasmuch as many cases might occur in which one would have need of the love and sympathy of others, and in which, by such a law of nature, sprung from his own will, he would deprive himself of all hope of the aid he desires.

These are a few of the many actual duties, or at least what we regard as such, which obviously fall into two classes on the one principle that we have laid down. We must be able to will that a maxim of our action should be a universal law. This is the canon of the moral appreciation of the action generally. Some actions are of such a character that their maxim cannot without contradiction be even conceived as a universal law of nature, far from it being possible that we should will that it should be so. …

How do we recognize duties from mere options?

We have thus established at least this much, that if duty is a conception which is to have any import and real legislative authority for our actions, it can only be expressed in categorical and not at all in hypothetical imperatives. We have also, which is of great importance, exhibited clearly and definitely for every practical application the content of the categorical imperative, which must contain the principle of all duty if there is such a thing at all. We have not yet, however, advanced so far as to prove à priori that there actually is such an imperative, that there is a practical law which commands absolutely of itself and without any other impulse, and that the following of this law is duty.

With the view of attaining to this, it is of extreme importance to remember that we must not allow ourselves to think of deducing the reality of this principle from the particular attributes of human nature. For duty is to be a practical, unconditional necessity of action; it must therefore hold for all rational beings (to whom an imperative can apply at all), and for this reason only be also a law for all human wills. …

What does Kant mean by saying that the human being is an “end”?

Now I say: man, and generally any rational being exists as an end in himself, not merely as a means to be arbitrarily used by this or that will, but in all his actions, whether they concern himself or other rational beings, must be always regarded at the same time as an end. All objects of the inclinations have only a conditional worth, for if the inclinations and the wants founded on them did not exist, then their object would be without value. But the inclinations, themselves being sources of want, are so far from having an absolute worth for which they should be desired that on the contrary it must be the universal wish of every rational being to be wholly free from them. Thus, the worth of any object which is to be acquired by our action is always conditional. Beings whose existence depends not on our will but on nature’s, have nevertheless, if they are irrational beings, only a relative value as means, and are therefore called things; rational beings, on the contrary, are called persons, because their very nature points them out as ends in themselves, that is as something which must not be used merely as means, and so far therefore restricts freedom of action (and is an object of respect). These, therefore, are not merely subjective ends whose existence has a worth for us as an effect of our action, but objective ends, that is, things whose existence is an end in itself; an end moreover for which no other can be substituted, which they should subserve merely as means, for otherwise nothing whatever would possess absolute worth; but if all worth were conditioned and therefore contingent, then there would be no supreme practical principle of reason whatever.

How does he use this idea to restate the Categorical Imperative into a Second Formulation?

If then there is a supreme practical principle or, in respect of the human will, a categorical imperative, it must be one which, being drawn from the conception of that which is necessarily an end for everyone because it is an end in itself, constitutes an objective principle of will, and can therefore serve as a universal practical law. The foundation of this principle is: rational nature exists as an end in itself. Man necessarily conceives his own existence as being so; so far then this is a subjective principle of human actions. But every other rational being regards its existence similarly, just on the same rational principle that holds for me: so that it is at the same time an objective principle, from which as a supreme practical law all laws of the will must be capable of being deduced. Accordingly, the practical imperative will be as follows: So act as to treat humanity, whether in thine own person or in that of any other, in every case as an end withal, never as means only. We will now inquire whether this can be practically carried out.

How does Kant reconsider the earlier four examples in light of this new formulation?

 To abide by the previous examples:

Firstly, under the head of necessary duty to oneself: He who contemplates suicide should ask himself whether his action can be consistent with the idea of humanity as an end in itself. If he destroys himself in order to escape from painful circumstances, he uses a person merely as a means to maintain a tolerable condition up to the end of life. But a man is not a thing, that is to say, something which can be used merely as means, but must in all his actions be always considered as an end in himself. I cannot, therefore, dispose in any way of a man in my own person so as to mutilate him, to damage or kill him. (It belongs to ethics proper to define this principle more precisely, so as to avoid all misunderstanding, e.g., as to the amputation of the limbs in order to preserve myself, as to exposing my life to danger with a view to preserve it, etc. This question is therefore omitted here.)

Secondly, as regards necessary duties, or those of strict obligation, towards others: He who is thinking of making a lying promise to others will see at once that he would be using another man merely as a mean, without the latter containing at the same time the end in himself. For he whom I propose by such a promise to use for my own purposes cannot possibly assent to my mode of acting towards him and, therefore, cannot himself contain the end of this action. This violation of the principle of humanity in other men is more obvious if we take in examples of attacks on the freedom and property of others. For then it is clear that he who transgresses the rights of men intends to use the person of others merely as a means, without considering that as rational beings they ought always to be esteemed also as ends, that is, as beings who must be capable of containing in themselves the end of the very same action.

Thirdly, as regards contingent (meritorious) duties to oneself: It is not enough that the action does not violate humanity in our own person as an end in itself, it must also harmonize with it. Now there are in humanity capacities of greater perfection, which belong to the end that nature has in view in regard to humanity in ourselves as the subject: to neglect these might perhaps be consistent with the maintenance of humanity as an end in itself, but not with the advancement of this end.

Fourthly, as regards meritorious duties towards others: The natural end that all men have is their own happiness. Now humanity might indeed subsist, although no one should contribute anything to the happiness of others, provided he did not intentionally withdraw anything from it; but after all, this would only harmonize negatively not positively with humanity as an end in itself, if everyone does not also endeavor, as far as in him lies, to forward the ends of others. For the ends of any subject which is an end in himself ought as far as possible to be my ends also if that conception is to have its full effect with me.

This principle, that humanity and generally every rational nature is an end in itself (which is the supreme limiting condition of every man’s freedom of action), is not borrowed from experience, firstly, because it is universal, applying as it does to all rational beings whatever, and experience is not capable of determining anything about them; secondly, because it does not present humanity as an end to men (subjectively), that is as an object which men do of themselves actually adopt as an end; but as an objective end, which must as a law constitute the supreme limiting condition of all our subjective ends, let them be what we will; it must therefore spring from pure reason. In fact the objective principle of all practical legislation lies (according to the first principle) in the rule and its form of universality which makes it capable of being a law (say, e.g., a law of nature); but the subjective principle is in the end; now by the second principle, the subject of all ends is each rational being, inasmuch as it is an end in itself. Hence follows the third practical principle of the will, which is the ultimate condition of its harmony with universal practical reason, viz.: the idea of the will of every rational being as a universally legislative will. (Dimock and Fischer, Ch. 4)

Strengths and Weaknesses of Kant’s Deontology

Here are some of the main strengths and weaknesses attributed to the deontological ethics of Immanuel Kant:


  1. Kant’s theory emphasizes moral absolute duties that are not contingent on particular circumstances or consequences. This strictness appeals to our moral intuition.  Kantian ethics gives us a great tool to keep us from justifying our actions in order to come to some predetermined conclusion.
  2. Kant rightly points out that consequences are a dangerous consideration in ethics because they are ultimately unknown.
  3. It values all rational beings as “ends in themselves” due moral respect, and rejects the idea that persons can be used as means to an end.
  4. It derives duties rationally through consistent tests like universalization, aligning obligation with reason and autonomy.  Kantian ethics has the strength of providing a logical path to moral decisions that can be discovered by religious and non-religious alike. By using the universalizing process anyone can determine the right action based on Good Will.
  5. It explains the objective necessity and authority we attribute to moral commands.


  1. Kant has been accused of undue rigidity in advocating rule-based obligations, and of lacking flexibility when confronted by situational factors in decision-making.
  2. If acting purely from duty a person may be found guilty of a form of play-acting. For instance, an acquaintance might help you move and stays at the task all day long. You may think your acquaintance is acting like a good friend and perhaps he likes you better than you previously thought. At the end of the move, you say to him, “Thanks for helping me move. You acted as a great friend.” He replies, “Well, we all have duties to help others when we can. I was invited to play golf today, but I realized you had no one to help and it was my duty to help you, so I passed on playing golf.” Suddenly you realize he is serious. He does not care for you, he is only interested in doing his cold, sober duty.
  3. Kant overemphasizes reason and thereby diminishes other moral faculties like emotions, care, and relationships.
  4. The universalizability test struggles with complex conflicts of duties and exceptions in application.  Very often duties conflict with each other and Kant offers no way of knowing which duty is the more important in such cases. For example, one day you hear a knock on the door. You open the door and the Nazi officer bursts in and shouts, “Where are the Jews?” You know quite well that the Jews are hidden in the attic. Now, you have two absolute duties vying for your attention: the duty to uphold one’s promises (in this case, to the Jews) and the duty to tell the truth (to the Nazis). It seems you cannot perform your duty to one without violating the other. What do you do?
  5. There seems to be no clear duty in Kant’s thinking to maximize overall welfare or prefer the most ethical option.


Works Cited

Bause, Johann Friedrich. “Bildnis-Des-Immanuel-Kant-Johann-Friedrich-Bause-Verlagsort-Leipzig-1791-Berlin-Staatsbibliothek-Zu-Berlin.” Wikimedia Commons, Wikimedia Commons, 12 Sept. 2016, https://commons.wikimedia.org/wiki/File:Bildnis-des-immanuel-kant-johann-friedrich-bause-verlagsort-leipzig-1791-berlin-staatsbibliothek-zu-berlin.jpeg. Accessed 5 Apr. 2022.

CrashCourse. Kant & Categorical Imperatives: Crash Course Philosophy #35. YouTube, YouTube, 14 Nov. 2016, https://youtu.be/8bIys6JoEDw. Accessed 5 Apr. 2022.


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PPSC PHI 1011: The Philosopher's Quest by Daniel G. Shaw, Ph.D. is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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