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Why Friendship Is Essential to a Good Life

Plato and Aristotle, detail from The School of Athens by Raphael
‘Plato is dear, but dearer still is truth’—a saying that captures Aristotle’s willingness to disagree with his teacher in the pursuit of truth, and his conviction that genuine friendship need never fear honest disagreement.

By Dr Neel Burton — Psychiatrist, philosopher, and wine writer; Fellow of Green Templeton College, University of Oxford; author of over twenty books.

We have never had so many ways of connecting with other people, and yet so few close friends.

Many of us have hundreds or even thousands of online contacts, but no one we could call in the middle of the night. We move cities, change jobs, change partners, and change phones without thinking twice, and our friendships often prove just as disposable.

Aristotle would have regarded this not merely as a social problem, but as a human tragedy.

‘Without friends,’ he writes in the Nicomachean Ethics, ‘no one would choose to live, though he had all other goods.’

It is a remarkable claim.

Most of us think that, given enough money, success, health, freedom, and comfort, we could muddle along well enough on our own. Aristotle thought otherwise. Friendship is not simply one of life’s pleasures. It is one of its necessities.

Why We Need Friends

The ancient Greeks had several words for love, including eros for passionate or romantic love, and philia (the root of ‘bibliophile’ and ‘anglophile’) for friendship.

For Aristotle, philia is a virtue which is ‘most necessary with a view to living … for without friends no one would choose to live, though he had all other goods.’ 

Philia underpins not only personal happiness but the very health of the state. Friendship fosters trust, cooperation, generosity, forbearance, and even justice—for when friendship exists, justice is scarcely needed.

But friendship is not simply for enjoying and getting along. In its highest form, it is a vehicle of virtue, helping us to become better people.

The Three Forms of Friendship

Aristotle begins with a broad or minimal concept of philia. For one person to be friends with another, it is necessary, simply, ‘that [they] bear good will to each other, without this escaping their notice’.

A person may bear goodwill to another for one of three reasons: that they are useful; that they are pleasant; or that they are good—that is, rational and virtuous.

Friendships of utility are based on mutual advantage. We enjoy one another’s company because each has something to offer the other. Such friendships are common in business, politics, and everyday life, and there is nothing wrong with them. But remove the advantage, and they usually disappear.

Friendships of pleasure are based on enjoyment. We like another person’s wit, humour, charm, or shared interests. These friendships are especially common among the young, whose lives are often governed more by feeling than by settled character. They, too, tend to fade as tastes and circumstances change.

The highest form of friendship is based not on usefulness or pleasure, but on virtue. ‘Perfect friendship’, says Aristotle, is ‘the friendship of men who are good, and alike in virtue.’

Perfect friends are drawn to each other not because they expect anything in return, but because they genuinely admire and value one another’s character. They love their friend not for what he has or provides, but for who he is. 

Now those who wish well to their friends for their sake are most truly friends; for they do this by reason of their nature and not incidentally; therefore their friendship lasts as long as they are good—and goodness is an enduring thing … And such a friendship is as might be expected permanent, since there meet in it in all the qualities that friends should have.

Another Self

A perfect friend, says Aristotle, is ‘another self’.

This does not mean someone who merely resembles us or always agrees with us. It means someone who cares enough, or is noble enough, to disagree with us and challenge us.

A true friend shares our deepest values, but also helps us to live up to them. We become better not by admiring virtue from afar, but by practising it together. Friendship is not merely the reward of virtue; it is one of the principal ways in which virtue is cultivated.

Every act of friendship is also an exercise in virtue. In being patient with our friend, we become more patient ourselves. In speaking honestly, we become more honest. In encouraging what is best in another person, we strengthen what is best in ourselves. Our good and their good are no longer competing like fishmongers: each one’s happiness adds to that of the other. We become, in the deepest sense, another self.

We may find an illustration of this ideal in Plato’s Phaedrus. Socrates and Phaedrus spend an afternoon walking in the Attic countryside while reflecting on the soul, love, and the art of persuasion. Their friendship is grounded not merely in pleasure, but in a shared pursuit of truth. At the end of their conversation, Phaedrus responds to Socrates’ prayer with the simple request: ‘Ask the same for me, for friends should have all things in common.’ Whether or not Aristotle had this dialogue in mind, it beautifully embodies his conception of perfect friendship.

Why Friendship Is Rare

Unfortunately, perfect friendship is uncommon.

First, it requires good character, and good character is itself uncommon. Second, it demands something that has always been scarce and may never have been scarcer than today: time.

Friendship cannot be hurried.

People only come to know one another by sharing experiences, surviving disappointments, forgiving offences, and gradually learning that they can be trusted. Like character itself, friendship grows slowly.

We live in a culture that prizes speed, convenience, novelty, and consumer choice. Relationships, like everything else, are expected to fit around our schedules and satisfy our needs. Friendship asks something very different of us. It requires attention, loyalty, respect, forbearance, and sometimes considerable sacrifice.

The Courage to Be Known

There is another difficulty.

Many of us have become so unaccustomed to genuine friendship that, when we encounter its possibility, we instinctively retreat from it.

A true friend is not simply someone who makes us feel better. He knows us. He sees through our pretences. He notices when we deceive ourselves. He quietly expects us to become better than we are.

That can be deeply unsettling.

We often say that we want people to accept us exactly as we are. Aristotle might have replied that a friend accepts us as we are while refusing to leave us there.

Perhaps that is why perfect friendship is so rare. It demands not only affection, but humility; not only loyalty, but the willingness to be changed.

Nowadays, it is all too easy to retreat into comfortable mediocrity.

Friendship and Happiness

Throughout the Nicomachean Ethics, Aristotle argues that happiness lies not in pleasure or success, but in living according to reason and virtue.

Friendship is one of the principal ways in which this becomes possible.

A good friend encourages what is best in us, restrains what is worst, and accompanies us in the long and difficult work of becoming the person we are capable of being. If we abandon a true friend, really, it is our own self that we are abandoning.

We tend to think of friendship as one of life’s pleasures.

Aristotle thought of it as one of life’s disciplines.

A good friend does not simply make us happier.

He helps us become better and bigger.

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How Socrates, Plato, and Aristotle Reimagined Happiness

The Death of Socrates, by David
The Death of Socrates, by David

By Dr Neel Burton — Psychiatrist, philosopher, and wine writer; Fellow of Green Templeton College, University of Oxford; author of over twenty books.

We all say we want to be happy, but the pursuit of happiness often seems like a wild goose chase.

Maybe the problem is not so much with us, or the world we live in, but with the very concept of happiness.

The ancient Greeks had a much better concept. They called it eudaimonia, literally ‘good soul’, ‘good spirit’, or ‘good god’.

Although Socrates, Plato, and Aristotle understood eudaimonia in somewhat different ways, they all regarded it as the highest good, often even the very aim and purpose of philosophy.

What Is Eudaimonia?

Eudaimonia is often translated from Greek simply as ‘happiness’—but that is very misleading. The word ‘happy’, which is related to ‘happen’ and ‘perhaps’, derives from the Norse happ for ‘chance’, ‘fortune’, or ‘luck’. From Irish to Greek, most European words for ‘happy’ originally meant something like ‘lucky’—one exception being Welsh, in which it originally meant ‘wise’.

Another word for ‘happy’ or ‘fortunate’ in Old English is gesælig, which, over the centuries, morphed into our ‘silly’.

Eudaimonia, in contrast, is anything but silly. It has nothing to do with luck and everything to do with hard work. It is a much deeper, fuller, and richer concept than happiness, sometimes articulated in terms of flourishing or living a life that is worthwhile or fulfilling.

Many philosophical schools in antiquity thought of eudaimonia as the highest good, although schools such as Epicureanism and Stoicism conceived of it in somewhat different terms.

What can be said is that, unlike happiness, eudaimonia is not an emotion but a state of being—or even, especially for Aristotle, a state of doing. As such, it is more stable and reliable, and cannot so easily be taken away from us. Although it leads to pleasure or satisfaction of the deepest kind, it does not come from pleasure, but is according to higher values and principles that transcend the here and now.

The idea of eudaimonia evolved over time, especially across the three generations that separated Socrates, via Plato, from Aristotle—the three greatest philosophers of antiquity.

Socrates on Eudaimonia

Socrates, from what we can tell (mainly from his student Plato), equated eudaimonia with wisdom and virtue. In the Greater Alcibiades, he says that he who is not wise cannot be happy; in the Gorgias, that nothing truly bad can ever happen to a good man; and in the Meno, that everything the soul endeavours or endures under the guidance of wisdom ends in happiness.

In the Apology, at his trial, Socrates gives a defiant defence, telling the jurors that they ought to be ashamed of their eagerness to possess as much wealth, reputation, and honour as possible, while not caring for or giving thought to wisdom or truth, or the best possible state of their soul. ‘Wealth,’ he says, ‘does not bring about excellence, but excellence makes wealth and everything else good for men, both individually and collectively.’

Socrates provided the ultimate proof of his principle that ‘nothing truly bad can ever happen to a good man’. When the jurors condemned him to death, they only made him and his ideas immortal—and he did all he could not to prevent that from happening. 

Plato on Eudaimonia

Plato was inspired by the example of Socrates. In the Republic, Plato’s brother Glaucon argues that most people are fundamentally selfish, but maintain a reputation for virtue and justice to evade the social costs of being or appearing unjust. But if a man could get hold of the mythical Ring of Gyges and make himself invisible, he would most surely behave as it suited him:

No man would keep his hands off what was not his own when he could safely take what he liked out of the market, or go into houses and lie with any one at his pleasure, or kill or release from prison whom he would, and in all respects be like a god among men.

We behave justly not because we value justice, but because we are weak and fearful; while the unjust man who is cunning enough to seem just will get the better of everyone and everything.

As part of his lengthy reply to Glaucon, Plato famously conjures up an idealised Republic to help him ‘locate’ (define) justice, first in the state and then in the individual. Plato argues that justice and injustice are to the soul as health and disease are to the body: If health in the body is intrinsically desirable, then so too is justice in the soul. For Plato, an unjust man cannot be happy because he is not in rational and ordered control of himself.

Aristotle embraced much of Plato’s account, but gave eudaimonia a broader and more practical meaning.

Aristotle on Eudaimonia

It is with Plato’s one-time student Aristotle and his Nicomachean Ethics that the concept of eudaimonia is most closely associated.

For Aristotle, a thing is best understood by looking at its end, purpose, or goal. For example, the purpose of a knife is to cut, and it is by seeing this that one best understands what a knife is; the goal of medicine is good health, and it is by seeing this that one best understands what medicine is, or ought to be.

Now, if one does this for some time, it soon becomes apparent that some goals are subordinate to other goals, which are themselves subordinate to yet other goals. For example, a medical student’s goal may be to qualify as a doctor, but this goal is subordinate to her goal to heal the sick, which is itself subordinate to her goal to make a living by doing something useful. This could go on and on, but unless the medical student has a goal that is an end in itself, nothing that she does is actually worth doing.

What, asks Aristotle, is this goal that is an end in itself? This ‘supreme good’, he replies, is eudaimonia, and eudaimonia only.

But what exactly does Aristotle mean by eudaimonia?

For Aristotle, it is by understanding the distinctive function of a thing that one can understand its essence. Thus, one cannot understand what it is to be a gardener unless one can understand that the distinctive function of a gardener is ‘to tend to a garden with a certain degree of skill’.

Whereas human beings need nourishment like plants, and have sentience like animals, their distinctive function, says Aristotle, is their unique and god-like capacity to reason. Thus, our supreme good is to lead a life that enables us to use and develop our reason, and that is in accordance with reason.

By living our life to the full according to our essential nature as rational beings, we are bound to flourish, that is, to develop and express our full human potential, regardless of the ebb and flow of our good or bad fortune.

To put this in modern terms, if we develop our thinking skills, if we guard against lies and self-deception, if we train and master our emotions, we will, over the years, make better and better choices, do more and more meaningful things, and derive ever-increasing satisfaction from all that we have become and all that we have done, and are yet able to do.

Although Aristotle’s account proved the most influential, his was not the last word on the matter. The Cynics, Stoics, Epicureans, and Skeptics all regarded eudaimonia as the highest good, although they conceived of it in somewhat different terms. For the Cynics and Stoics, happiness depended less on flourishing than on living in accordance with nature and reason, and on cultivating an inner freedom that no amount of bad fortune could destroy. The Epicureans sought tranquillity through moderation, friendship, and freedom from unnecessary desires, while the Skeptics argued that peace of mind arises from suspending judgement about matters that cannot be known with certainty.

In recent decades, philosophers and psychologists have rediscovered eudaimonia as an alternative to the modern pursuit of pleasure or subjective happiness. Increasingly, they recognise that a good life depends not only on how we feel, but also on how we live.

‘Happiness’ is something that comes and goes. It is at the mercy of fortune and circumstance. A life well lived, however, is a treasure that no one and nothing can ever take away from you, and that will shine in the eyes of others long after you are dead.

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Getting to the Real Immanuel Kant

A young Immanuel Kant (the Becker portrait)
Without communication, love does not exist; without respect, it does not endure. —Immanuel Kant

By Dr Neel Burton — Psychiatrist, philosopher, and wine writer; Fellow of Green Templeton College, University of Oxford; author of over twenty books.

Immanuel Kant is often remembered as the driest of philosophers: austere, methodical, and so punctual that the people of Königsberg supposedly set their clocks by his daily walk. Yet beneath the formidable reputation lay a surprisingly warm and personable man. His greatest transformation came not through philosophy, but through friendship.

In his youth and middle age, the sharply dressed Immanuel Kant (1724–1804) moved in Königsberg’s most refined circles and often stayed out into the small hours. In this period, his student Johann Gottfried Herder described him as ‘the most urbane fellow in the world.’

But when Kant turned forty, he underwent a midlife transformation. He quite literally sobered up, abandoning carefree carousing for the disciplined life of the mind. This profound change owed as much to the early death of a close friend, the dissolute Johann Daniel Funk, as to the making of a new friend, the English merchant Joseph Green, who lived by the clock.

Kant essentially adopted Green’s modus vivendi.

Kant’s Daily Routine, and How It Helped Him

For the rest of his productive life, Kant employed a retired soldier, Martin Lampe, to wake him up at precisely five-to-five every morning. Lampe would stride into his master’s bedroom and cry out, “Herr Professor, the time is come!” Or in German, Herr Professor, es ist Zeit!

Kant worked at his desk in his nightclothes until his lectures began at seven. At eleven, he would change back into nightclothes and return to his desk. The working day effectively ended at one, when he would take lunch in company in a public inn or restaurant. Lunch would end at three with a round of manufactured jokes—in the belief that laughter was good for digestion and broader health.

After lunch, Kant would take his daily constitutional around Königsberg. He walked alone, from fear that outdoor conversation would lead him to breathe through the mouth. He often wound up at Green’s, with whom he liked to discuss Hume and Rousseau. It is said that the housewives of Königsberg would set their timepieces by the time—seven sharp—at which he left Green’s house.

By automating trivial daily decisions, Kant’s rigid daily routine freed his mind to focus purely on philosophy. It’s because of Kant that I have six of the same shirt.

Kant’s Jokes and Philosophy of Laughter

What kind of jokes did Kant tell after lunch? Some of his jokes have come down to us in his writing. For instance: A man tried to arrange a solemn funeral for a rich relative, but failed in the task: ‘The more I paid my mourners, the merrier they looked.’ A merchant sailed back from India with his fortune, but, in a violent storm, had to throw all his cargo overboard. This upset him so much that his wig turned grey overnight.

Laughter, Kant thought, “is an affect resulting from the sudden transformation of a heightened expectation into nothing.” The mind is deceived into tensing up, but with the deception revealed suddenly relaxes, leading to laughter, which mimics the motions of the mind and is extremely health-giving. Kant never laughed at his own jokes, but always kept a straight face.

In The Critique of Judgement (1790), Kant quoted Voltaire in saying that Heaven had given us two comforts against life’s hardships, hope and sleep—before suggesting that Voltaire ‘could have added laughter’.

The Death of Joseph Green

In 1786, Joseph Green died, deeply affecting Kant, who thereafter became much more housebound.

After a suitable period of mourning, Kant recruited a female cook and began hosting protracted lunches aimed at stimulating the play of thoughts. To this end, he gathered guests from diverse backgrounds and perspectives, believing that the ideal number of guests lay somewhere between that of the Graces and the Muses (three and nine). All topics great and small were on the table. Philosophy was allowed but not dogmatism, for fear that it would interrupt the convivial flow of ideas.

As well as wine (another of God’s comforts), Kant had a taste for Königsberger Klopse (meatballs in a creamy white sauce with capers), Teltow turnips (an heirloom turnip from the Berlin-Brandenburg region), roast beef, cod, and, as a condiment for the above, English mustard, which he mixed himself in the belief that his special mix protected against senescence.

Kant’s Philosophy of Friendship

Joseph Green was the closest friend that Kant ever had. Green inspired Kant’s routine and became his philosophical sounding board. Kant allegedly discussed every single sentence of the Critique of Pure Reason with Green before publishing it in 1781.

In the Metaphysics of Morals (1797), Kant ended his discussion of character traits just as, in the Nicomachean Ethics, Aristotle ended his discussion of the same: with an analysis of friendship.

In the Nicomachean Ethics, Aristotle made much of the idea of ‘perfect friendship’, which, he thought, is only possible between people of reason and virtue. He famously described a perfect friend as ‘another self’—later paraphrased by Diogenes Laertius as ‘a single soul dwelling in two bodies.’

Kant deemed ‘perfect friendship’ an ideal that in practice cannot be attained. But in striving for it, we might nonetheless arrive at ‘moral friendship’, in which two persons feel able to disclose their secret thoughts and feelings to each other. Moral friendship requires a savant mélange of love and respect, love for bringing two people together, and respect for not driving them apart by infringing upon their dignity and autonomy.

From his own experience, Kant came to believe that most people cannot develop their true character until middle age, when they might undergo a ‘rebirth’. At twenty, we are no more than the product of our upbringing and environment. At thirty, we are still reliant on the judgement and approval of others. Only at forty are we confident enough (or perhaps tired enough) to become who we truly are.

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Kant’s philosophy cannot be fully understood in isolation. The German Greeks places him within the great tradition of German philosophy, from Leibniz through Hegel and Schopenhauer to Nietzsche—revealing how these thinkers transformed the legacy of ancient Greece.

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Nietzsche on Master and Slave Morality—and Why You May Be Both

A greek marble statue juxtaposed with a crucifix.

By Dr Neel Burton — Psychiatrist, philosopher, and wine writer; Fellow of Green Templeton College, University of Oxford; author of over twenty books.

Essay substantially revised on 16 August 2026.

In 1885, Nietzsche’s sister Elisabeth married Bernhard Förster, a high school teacher turned German nationalist and rabid antisemite. Nietzsche so disapproved that he did not attend the wedding.

In 1886, Förster and Elisabeth left for Paraguay with fourteen German families to establish a vegetarian and teetotal colony, Nueva Germania, that admitted only ‘racially pure’ Germans. While Elisabeth played the princess, the heavily indebted Förster drank heavily and became depressed. In 1889, he committed suicide in a hotel room in San Bernardino.

Nietzsche looked upon nationalism and democracy as the successors of the ‘slave morality’ of Christianity. Instead, he championed the ideal of the ‘good European’, a cosmopolitan, supra-national individual who transcends petty national and religious prejudices and strives to unite Europe through a new, higher cultural synthesis. In 1886, the year that Elisabeth left for Paraguay, he wrote to his mother from the Swiss Alps, ‘Even if I should be a bad German, I am at all events a very good European.’

Despite his contempt for nationalism, Nietzsche’s philosophy would later be appropriated by German nationalists and Nazis, helped along by Elisabeth after his collapse into insanity. Nietzsche held every herd in contempt, whether Christian, democratic, or nationalist. But he reserved his highest contempt for the nationalist herd.

Herd Mentality

In 1886, Nietzsche broke with his publisher Ernst Schmeitzner, an antisemite who had been publishing antisemitic literature and propaganda while neglecting Nietzsche’s work.

In that year, Nietzsche also published a new book, Beyond Good and Evil (1886). As the title suggests, this is not a work of normative ethics (what is good and evil) but of meta-ethics (what is meant by ‘good’ and ‘evil’). Nietzsche portrays the life-denying Western religion, morality, and philosophy as rooted in a ‘herd mentality’, and calls for the abandonment of binary morality. After the death of God, there can no longer be a universal perspective. Therefore, there can no longer be an objective truth. Although philosophical systems purport to be objective, they are no more than the ‘involuntary and unconscious memoirs’ of their prejudiced authors. ‘Truth’ is no more than ‘the kind of error without which a certain species of life could not live’.

Master vs Slave Morality

In Beyond Good and Evil, Nietzsche also introduces the dichotomy between master and slave morality. Slave morality is often confused with herd mentality, but can be understood more precisely as a component and expression of herd mentality. If slave morality arises out of the resentment-driven inversion of values created by the weak in revenge against the strong, herd mentality is the broader mediocrity that enforces conformity and suppresses individuality.

For Nietzsche, modern society represents the triumph of Judeo-Christian slave morality over the older Greco-Roman master morality. Master morality originates in the strong, and is marked by values such as pride, nobility, courage, truthfulness, health, creativity, and joy. The Homeric era of Achilles and Odysseus was a pure expression of master morality, a time when actions were either noble or base, rather than good or evil.

Achilles does not apologise for seeking kleos, or glory. Homer does not ask his heroes to be humble or compassionate. Their virtues are precisely those qualities which distinguish them from other men: courage, strength, cunning, eloquence, and the capacity for magnificent deeds. The Greek word aretē, usually translated as ‘virtue’, originally carried the broader sense of excellence, and in Aristotle virtue blends with excellence. Aristotle doesn’t even know what forgiveness means—because the concept hadn’t quite been invented.

So, too, any one can get angry—that is easy—or give or spend money; but to do this to the right person, to the right extent, at the right time, with the right motive, and in the right way, that is not for every one, nor is it easy; wherefore goodness is both rare and laudable and noble. —Aristotle, Nicomachean Ethics

Slave morality, in contrast, is the envious and vengeful reaction of the mild and mediocre to the oppression of the masters, to create an inverted morality by turning their weakness into virtue and the virtues of the masters into vice.

Thus, slave morality is marked by values such as humility, meekness, conformity, patience, compassion, and pity. Christianity is called the religion of pity, which deprives us of strength and makes suffering contagious. In master morality, the good is whatever is good for the masters; in slave morality, it is whatever constrains and emasculates the masters. By pretending that humility and docility are a moral choice, slave morality manufactures an ideal out of impotence and subjugation. Thus, pride becomes a vice or sin, humility is elevated into a supreme virtue, and the son of God washes the feet of his disciples and allows himself to be crucified like a common criminal.

What This Means in Us

Slave morality is a cynical and pessimistic inverse morality that involves the systematic subversion of the old, natural master morality. It seeks not to transcend master morality, but, through ‘priestly vindictiveness’, to emasculate and enslave the strong by persuading them that their strength is an evil. Democracy, with its fixation on equality, is in fact the heir to Christianity, even if most democrats would rather trace their lineage to Ancient Athens. God may be dead, but Christian values survive God, sometimes in other forms.

But for all that, the old Greco-Roman morality, because it reflects reality and the natural impulse, cannot be vanquished, and vies with the inverted Judeo-Christian morality. Modern man is confused because he has constantly to juggle their contradictions, while himself being neither Christian nor Ancient but drifting in an ill-defined no-man’s land. Thus, he is taught to admire humility, while being told to believe in himself. He condemns pride, but values ambition. He insists upon equality while idolising exceptional athletes, artists, and entrepreneurs. He preaches self-sacrifice, but also self-realisation; contentment, but also achievement; meekness, but also assertiveness. In sum, he wants to be good, while also wanting to be great.

But might these two things be incompatible?

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Would You Lie to Save an Innocent Life?

Kant insisted that we should never lie—not even to a killer at the door.
Kant insisted that we should never lie—not even to a killer at the door.

By Dr Neel Burton — Psychiatrist, philosopher, and wine writer; Fellow of Green Templeton College, University of Oxford; author of over twenty books.

Essay substantially revised on 24 July 2026.

Imagine a killer at your door asking whether the person hiding in your house is there. Would you tell a lie? Most of us would. Immanuel Kant thought we shouldn’t. For Kant, lying is always wrong, no matter the circumstances.

Despite his love of hosting, conversation, and fine dining, Kant’s house was unadorned and austere. He had only one picture, which hung above his bureau. This picture was of Jean-Jacques Rousseau, who was only 12 years older than him. According to lore, the only time Kant failed to take his daily walk was when he received his copy of Rousseau’s Émile.

How did Rousseau’s outlook work its way into Kant’s moral philosophy? If, for Rousseau, it is by following the ‘general will’ that we can be said to be free, for Kant, it is by obeying those moral laws that we would will as universal laws. Moral laws that we would will as universal laws are given not by our individual will but by our rational will, which we have in common with all other rational beings.

We often experience this dichotomy in our minds: this is what I selfishly or frivolously want to do, and this is what I truly ought to do—because I want to live in a better society that abides by this rule, and would resent it if other people behaved in such a biased, thoughtless way.

To conform to the universal law is not to be a slave; on the contrary, it is to follow reason and free ourselves from our irrational and disordered appetites. For Kant, this capacity to overrule our individual will lies at the heart of our special dignity as human beings.

For Kant, morality rests not on God, tradition, authority, or emotion, but on reason itself. Through the Categorical Imperative, he sought to place morality on an objective, rational foundation. Since all rational beings share the same rational nature, they should arrive at the same moral principles if they reason correctly.

The Categorical Imperative vs. the Golden Rule

When obeying those moral laws that we could consistently and rationally will as universal laws, we are following the so-called Categorical Imperative, which might be re-stated as, ‘Always act such that the maxim of your action can at the same time be upheld as a universal law.’

This is similar to the much older Golden Rule of the Bible, according to which we should treat others as we would want to be treated. But whereas the Golden Rule is based on personal desire, which is subjective (I might, for example, be a masochist, or be willing to tolerate a degree of mistreatment), the Categorical Imperative is based on reason, which is objective.

Hypothetical Imperatives and Consequentialism

Hypothetical imperatives are practical rules for achieving a desired outcome, for example, ‘If you want to lose weight, you should watch what you eat.’ If you do not desire a particular outcome, you do not need to follow the rules. In this much, hypothetical imperatives are conditional and contingent. Categorical Imperatives, in contrast, are universal moral commands that bind everyone regardless of their aims, for example, ‘Do not lie’ or ‘Do not steal.’

Hypothetical imperatives answer to the lower faculty of desire, which aims at pleasure. Categorical Imperatives answer to the higher faculty of will, which functions rationally and autonomously by following the laws which it legislates for itself, regardless of consequences or personal feelings.

For Kant, true moral actions must be motivated by duty, not some desired outcome. Thus, Kantian ethics are sometimes described as deontological, or duty-based, and contrasted with consequentialism (for example, utilitarianism), which is outcome-based. For Kant, moral systems based on outcomes or desires, such as utilitarianism, operate on hypothetical imperatives, not true moral law.

Perfect vs. Imperfect Duties

Kant provides some examples to add flesh to the bones of the Categorical Imperative. Imagine a person in financial need who borrows money and promises to pay it back, in the knowledge that they never will. If this action were universalised, promises of repayment would no longer be believed, and the entire practice of lending would collapse. Kant also points out that abusing the lender in this way reduces a dignified being with ends of his own to a mere means to an end (‘Act always treating humanity, in yourself and others, as an end and never merely as a means’ is the second formulation of the Categorícal Imperative).

Second, imagine a person who does not intervene to help a person in distress. Were this maxim to be universalised, no one would ever help anyone, making the world a worse place.

In the first case, not repaying a loan, the maxim cannot be universalised because it would involve a contradiction. In the second case, not helping a person in distress, there is no such contradiction. Nonetheless, it would not be rational to will a world in which no one ever helped anyone. Whereas repaying a loan is a ‘perfect duty’, helping someone in need is an ‘imperfect duty’ in that we have some latitude in how we go about fulfilling it. Though we ought to be benevolent, we do not need to go about helping everyone all the time.

Failing in an imperfect duty, such as helping others or cultivating our talents, does not attract the same strict blame as violating a perfect duty, so long as we do not adopt a maxim contrary to the imperfect duty.

Kant’s Example of the Prudent Grocer

When we do help someone, our action must be motivated by duty if it is to have moral worth. If I help someone from inclination, for example, from sympathy or because it makes me feel good, I am still doing a praiseworthy thing, but my action, being circumstantial rather than principled and reliable, lacks moral worth.

Imagine a grocer who always gives the correct change, but only to avoid being caught and losing his reputation. His behaviour, though not blameworthy, is lacking in moral worth. If he knew that he could not get caught, he might behave differently and dishonestly. Because his behaviour is prudential and circumstantial, rather than born out of duty, it is not categorical.

For Kant, a paradigm of moral worth is the person who hates life and longs to commit suicide, but stays alive purely out of duty. Because this person has no self-serving inclinations, he is acting purely from duty, rather than mere ‘conformity to duty’. Similarly, a hard-hearted person who has no other motivation than duty has a moral worth ‘beyond all comparison the highest’.

How to Identify the Categorical Imperative

During his trial in Jerusalem in the 1960s, the Nazi Adolf Eichmann, a major organiser of the Holocaust, claimed to have been abiding by Kant’s Categorical Imperative—having interpreted ‘doing your duty’ as blind obedience to superior authorities.

To identify the Categorical Imperative, we need to look inward to our rational self and engage in our own moral reasoning—asking whether the maxim guiding our action could be universalised—rather than delegate responsibility to some external authority such as a dictator (say, Hitler) or even a religious doctrine (say, the Ten Commandments).

So long as they reason correctly, every rational being, human or otherwise, should be able to arrive at the same Categorical Imperative. As pure rational wills, shorn of our attributes, temperaments, and desires, we are all the same. Whenever we act with a moral dimension, we implicitly universalise that action for all other wills.

In her analysis of the Eichmann trial, the philosopher Hannah Arendt introduced the concept of the ‘banality of evil’, highlighting that evil can be perpetrated not only by fanatics and psychopaths, but, more ordinarily, by ‘normal’ people who fail to engage in critical self-reflection.

Constant’s Challenge: The Killer at the Door

In the aftermath of the Reign of Terror (1793-1794), a period during the French Revolution marked by mass executions of perceived enemies, the Swiss writer Benjamin Constant conceived of a thought experiment to undermine Kantian ethics.

Imagine a murderer at your door, asking where your friend, who has taken refuge in your house, is hiding. Although, according to Kant, lying is always wrong, it would be absurd to speak the truth and reveal your friend’s location to the murderer. In this scenario, the duty to protect your friend overrides any duty to tell the truth. Moreover, by intending to commit a grave injustice, the murderer has forfeited any right to the truth.

Kant responded to Constant in his 1797 essay, On a Supposed Right to Tell Lies from Benevolent Motives, and dug in his heels. Even in those circumstances, it would be wrong to lie. The morality of an action is determined by its principles, not its consequences. One could not know whether lying would do more good than harm to one’s friend in hiding. Whereas one would be responsible for the consequences of telling a lie, the consequences of telling the truth would be on the murderer. Moreover, to lie to the murderer would be to treat him as a mere means to an end, denying him the status of a rational being capable of free, reasoned action.

Whether or not we agree with Kant’s response, the Categorical Imperative continues to raise one of the deepest questions in ethics. Should moral principles admit exceptions, or do they cease to be moral principles once they do? More than two centuries later, the killer is still at the door, reminding us that the true test of morality comes not when doing the right thing is easy, but when it seems to cost us everything.

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To explore Kant’s ideas in their historical context—and discover how they influenced Hegel, Schopenhauer, and Nietzsche—see my book, The German Greeks.

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