Immanuel Kant: A Life in Five Chapters

Chapter 1 · The Harness-Maker's Son

Königsberg, and a life spent inside it

1724 – 1755 · Königsberg

Kant was born at Königsberg in East Prussia in 1724, the fourth of nine children of a harness-maker. Four of the nine survived childhood. The household was Pietist — an intense, inward, disciplined form of Lutheranism — and he was sent to a Pietist school where the day began before dawn with prayer and continued with more of it.

He hated it, and it is worth being precise about what he took from it. He kept a deep respect for conscience and for people who acted from principle, and he acquired a lasting dislike of religious display, of enthusiasm, and of being made to pray on a timetable. In later life he did not attend church and stopped joining the academic processions that ended in one.

His mother died when he was thirteen; he spoke of her with real warmth all his life and said she had opened his mind to the natural world. His father died when he was twenty-two, and he had to leave the university without a degree and work as a private tutor for families in the countryside for nine years.

He never travelled. The furthest he is known to have gone from Königsberg is a few dozen miles, for those tutoring posts. He never married. He lectured on geography for decades to people who had seen more of the world than he had, and did it from books.

This is the ordinary, narrow, provincial life out of which the most systematic moral philosophy in Europe came.

Why this matters

Almost everything distinctive in his ethics — conscience, duty, suspicion of religious feeling as a guide — has a visible root in the household and schooling he disliked.

What would you ask him about a life spent entirely in one city?

Ask Kant

• “What did the Pietist school actually do to you?”
• “Why did you stop attending church?”
• “What did those nine years as a tutor teach you?”
• “How do you lecture on geography without travelling?”
• “What did your mother show you about the natural world?”

Chapter 2 · Fifteen Years at the Door

Paid by the students who turned up

1755 – 1781 · Königsberg

Kant began lecturing at Königsberg in 1755 as a Privatdozent — an unsalaried lecturer paid directly by the students who chose to attend. He lectured on logic, metaphysics, physics, mathematics, geography, anthropology and education, sometimes twenty hours a week, for fifteen years, because he had to fill the hours to make a living.

He applied for chairs and did not get them. He was offered one in poetry and declined it. He was offered one at Erlangen and one at Jena and turned both down because he would not leave Königsberg. He finally became professor of logic and metaphysics in 1770, at forty-six.

Then almost nothing. For eleven years he published very little, and colleagues assumed he was finished. He was working on a problem he had described in a letter as the question of what the understanding contributes to what we know. The Critique of Pure Reason appeared in 1781, when he was fifty-seven. It was so difficult that almost nobody understood it, and he had to write a shorter version, the Prolegomena, to explain what the first one had been about.

The Groundwork of the Metaphysics of Morals followed in 1785, the Critique of Practical Reason in 1788, the Critique of Judgement in 1790. He produced the work he is known for between fifty-seven and sixty-six.

His routine in those years became famous: the same walk at the same hour, the same single meal a day taken with company, the same discipline that had got him through the fifteen years at the door.

Why this matters

It is the clearest case in philosophy of a system arriving very late from a person who had been obscure for decades, which is worth knowing before assuming that ideas belong to the young.

What would you ask him about eleven silent years?

Ask Kant

• “What were you doing in the eleven years you published nothing?”
• “Why refuse the chairs at Erlangen and Jena?”
• “Did being paid at the door change how you taught?”
• “Why was the first Critique so hard to read?”
• “What was the routine actually for?”

Chapter 3 · Dignity Rather Than Price

The idea everything else is built on

1785 · Königsberg

The Groundwork of 1785 contains the idea Kant is most admired for, and it can be stated in a sentence. Everything in the world has either a price or a dignity. What has a price can be replaced by an equivalent; what has a dignity has no equivalent and cannot be traded for anything. Rational beings have dignity.

From this he derives the rule that a person may never be treated merely as a means to somebody else's end. The word 'merely' does the work: you use a bus driver as a means to get across a city, and there is nothing wrong with that, because the arrangement is one they entered and could refuse. What is forbidden is handling a person purely as an instrument, in a way they could not possibly consent to.

He pairs it with the test everybody remembers: act only on a rule you could will to be a universal law. Ask what your action assumes, then ask whether the assumption could hold for everybody. A promise you intend to break relies on other people keeping theirs, so it cannot be universalised without destroying itself.

And he insists on something austere. An act has moral worth when it is done because it is right, not when it happens to coincide with what you wanted anyway. The shopkeeper who is honest because dishonesty is bad for trade has done the right thing for no moral reason at all.

That is the foundation. The next chapter is where it goes somewhere his admirers do not want to follow.

“Act in such a way that you treat humanity, whether in your own person or in the person of any other, never merely as a means to an end, but always at the same time as an end.”

— Kant, Groundwork of the Metaphysics of Morals (1785)

Why this matters

It is the source of the modern language of human dignity and of the idea that people cannot be traded off against outcomes — and it is the premise from which he reaches the scaffold.

What would you ask him about a value that cannot be traded for anything?

Ask Kant

• “What does the word 'merely' rule out, exactly?”
• “Is an honest shopkeeper doing anything morally worthwhile?”
• “How do I test whether a rule could be universal?”
• “What has dignity, and what only has a price?”
• “Does your ethics leave any room for feelings?”

Chapter 4 · The Last Murderer

Punishment, and the argument nobody expects

1797 · Königsberg

In the Metaphysics of Morals of 1797 Kant turned to punishment, and reached a conclusion that startles people who have just admired the formula of humanity.

His argument runs like this. If you punish a man in order to deter others, you are using him as an instrument for their benefit. If you punish him in order to reform him, you are using him for a purpose he has not chosen. Both treat him as a means. The only justification that respects him is that he has earned it: punishment is imposed because he has committed a crime, and in proportion to what he did. Anything else, he says, treats a person like a thing.

He then applies it. If a man has committed murder, he must die; there is no equivalent. He attacks Cesare Beccaria by name for arguing against capital punishment, calling the argument sentimental sympathy in the guise of principle.

And he gives the island. Suppose a civil society dissolved itself by common agreement — the people of an island deciding to scatter across the world. Even then, he says, the last murderer in prison ought first to be executed, so that everyone should understand the worth of their deeds, and so that bloodguilt does not cling to a people who failed to insist on the penalty. Nobody is being deterred. Nobody is being protected. That is precisely his point: the punishment is not for anything.

A learner does not have to agree. But they cannot dismiss it as vengeance, because it is derived from the value of the person being punished.

Why this matters

It is the retributive case at maximum strength, made from human dignity rather than from anger, and it is the argument any abolitionist position has to be able to answer.

What would you ask him about executing a man on an island that is about to be empty?

Ask Kant

• “Why is deterrence not a good enough reason to punish?”
• “What is the island example supposed to prove?”
• “Why did Beccaria's argument annoy you so much?”
• “Can a punishment respect the person it falls on?”
• “What if the courts get it wrong?”

Chapter 5 · Ordered to Be Quiet

Religion within the boundaries, and a royal rebuke

1793 – 1804 · Königsberg · Berlin

In 1793 Kant published Religion within the Boundaries of Mere Reason. Its argument is that what is valuable in religion is moral: that the doctrines worth keeping are the ones that can be given a moral meaning, and that the ecclesiastical apparatus around them is a shell which reason should be allowed to crack. He also insisted, in a way that upset both sides, that human beings have a real propensity to evil which no amount of good sense removes.

The Prussian censorship under Friedrich Wilhelm II had already refused part of it, and he had published by using the university's own authority. In October 1794 a royal order arrived, signed by the minister Wöllner: he was accused of distorting Christianity and required to promise that he would publish nothing further on religion.

He complied, and the way he complied is characteristic. He wrote back that as His Majesty's most loyal subject he would refrain — choosing the wording carefully, because a promise made to this king ended when this king did. Friedrich Wilhelm II died in 1797. Kant published on the matter again, and explained in print exactly what he had done and why.

He went on working until his mind began to fail. He died at Königsberg in February 1804, at seventy-nine. He was buried by the cathedral, in the city he had never left, and the townspeople came out in numbers that surprised everybody.

Why this matters

It shows a philosopher of principle handling state pressure by neither defying it nor surrendering to it, and the wording he chose is an argument in itself.

What would you ask him about a promise phrased so that it would expire?

Ask Kant

• “Why did you agree to stop writing about religion?”
• “What exactly did you promise the king?”
• “What is left of a religion once reason has finished with it?”
• “Why insist that people have a propensity to evil?”
• “Is obeying an unjust order ever compatible with duty?”

What Kant changed

Kant gave the modern world its language of human dignity and the idea that a person may not be traded against an outcome, which underlies every later declaration of rights. He also gave retributive justice its strongest philosophical form, derived from the worth of the offender rather than from public anger — so that arguments about punishment since have had to answer him rather than dismiss him.

A debate that continues

Whether Kant's retributivism actually follows from his own formula of humanity is a live dispute: critics argue that executing somebody treats them as a means to the vindication of the law, which is the very thing he forbids.

Keep exploring — ask Kant

• “Can a punishment respect the person it is inflicted on?”
• “Is an act worth less morally if you also wanted to do it?”
• “Does obeying an order you disagree with make you complicit in it?”

Related lives

• Jeremy Bentham — Who Wanted the Suffering Counted
• Jean-Jacques Rousseau — The Citizen · Father of Romanticism
• John Stuart Mill — Who Drew the Line Around Other People

Related themes

Crime and punishment · Capital punishment · Human rights · Moral philosophy