Kant's What Is Enlightenment? (1784): Dare to Know, Sapere Aude

What Is Enlightenment? is a short essay by the German philosopher Immanuel Kant, published in the December 1784 issue of the Berlinische Monatsschrift. In it Kant defined Enlightenment as humanity’s emergence from its “self-incurred immaturity” and gave the movement its best-known motto, sapere aude, “dare to know”. Only a few pages long, it remains one of the most widely read statements of what the Age of Enlightenment stood for.

Background: a question in a Berlin journal

By the 1780s the German word Aufklärung, meaning enlightenment, was in common use, but its meaning was hotly debated. The Berlinische Monatsschrift, founded in 1783 and edited by Johann Erich Biester and Friedrich Gedike, was the main voice of the Berlin Enlightenment and a forum for such discussions.

In its December 1783 issue, the Berlin clergyman Johann Friedrich Zöllner published an article defending religious marriage ceremonies. In a footnote he asked a pointed question: what is enlightenment? He complained that the term was used constantly but had never been properly answered. Several writers responded, most notably the Jewish philosopher Moses Mendelssohn, whose essay appeared in September 1784, and Kant.

Kant was by then 60 years old and a professor at the University of Königsberg in East Prussia, where he spent almost his whole life. His Critique of Pure Reason had appeared in 1781, and he was entering the most productive decade of his career.

Kant’s life in Königsberg was famously regular. He never travelled far from the city, yet it was a busy Baltic port with merchants and visitors from many countries, and he lectured on subjects ranging from logic and ethics to physical geography and anthropology. Only a month before his essay appeared, the Berlinische Monatsschrift had published another of his short works, the Idea for a Universal History with a Cosmopolitan Aim, which set out his hopes for a gradual improvement of human society.

The essay’s main arguments

Kant opened with a definition that has been quoted ever since. Enlightenment, he wrote, is humanity’s emergence from its self-incurred immaturity. By immaturity (Unmündigkeit, sometimes translated as “tutelage” or “nonage”) he meant the inability to use one’s own understanding without the direction of another person.

Such immaturity was “self-incurred”, Kant argued, when its cause was not a lack of intelligence but a lack of courage and resolution. Hence the motto he borrowed from the Roman poet Horace: sapere aude, “dare to know”, which he glossed as having the courage to use your own understanding.

Why do so many people remain immature? Kant blamed laziness and cowardice. It is comfortable to let a book think for you, a pastor serve as your conscience and a doctor decide your diet. Self-appointed “guardians” encourage this dependence by warning people how dangerous it is to walk alone.

For this reason Kant thought it difficult for individuals to free themselves. A whole public, however, could enlighten itself fairly easily, provided it was given freedom. Revolutions might overthrow despots but would not produce a real reform in ways of thinking; new prejudices would simply replace the old.

Public and private reason

The most original part of the essay distinguishes two uses of reason. The public use of reason is that of a scholar addressing the entire reading public through writing. This, Kant insisted, must always be free, because it is the only way enlightenment can spread.

The private use of reason is the reasoning a person may do in a particular civil post or office. Here freedom may legitimately be limited. An officer must obey orders while on duty, a citizen must pay taxes and a clergyman must teach according to his church’s creed. Yet as scholars, each may publicly criticise military errors, unjust taxes or church doctrine.

This distinction reverses modern usage, in which “public” often means official. For Kant, what is truly public is open discussion among free readers and writers, an idea that later thinkers connected to the concept of a public sphere.

Frederick the Great and the age of enlightenment

Kant wrote under the rule of Frederick II of Prussia (reigned 1740-1786), known as Frederick the Great, who was famous for his relative religious tolerance and his interest in philosophy. Kant called his time “the century of Frederick” and praised a ruler who left his subjects free to reason in matters of religion.

He summed up the ideal in a remark he attributed to Frederick: argue as much as you like and about whatever you like, but obey. Kant then drew a paradox: a greater degree of civil freedom seems good for freedom of mind yet sets limits to it, while a lesser degree of civil freedom, under a ruler secure enough not to fear his subjects’ thoughts, gives the spirit of free thought room to grow.

Asked whether his contemporaries lived in an enlightened age, Kant answered no; they lived in an age of enlightenment. The process had begun, especially in religion, but much remained to be done.

Kant also argued that no generation had the right to bind future generations to a fixed set of beliefs. A church council or a ruler that tried to freeze doctrine forever, preventing further growth in knowledge, would commit what he called a crime against human nature, whose essential destiny lay in progress. A people might accept a provisional order for a time, but must remain free to question and improve it.

Reception and critics

The essay was read alongside Mendelssohn’s answer, and Kant added a note saying he had not yet seen Mendelssohn’s piece when he sent his own. The Königsberg writer Johann Georg Hamann, a friend and critic of Kant, complained in a private letter that the essay blamed the immature while excusing their guardians.

The limits of Prussian tolerance soon became clear. After Frederick’s death in 1786, his successor Frederick William II introduced stricter religious censorship, and in 1794 Kant received a royal rebuke for his writings on religion and promised not to publish further on the subject during the king’s lifetime.

Timeline

• 1724, 22 April: Immanuel Kant is born in Königsberg, East Prussia.
• 1781: Kant publishes the Critique of Pure Reason.
• 1783, December: Johann Friedrich Zöllner asks “What is enlightenment?” in the Berlinische Monatsschrift.
• 1784, September: Moses Mendelssohn’s answer is published in the same journal.
• 1784, 30 September: Kant dates his essay in Königsberg.
• 1784, December: Kant’s essay appears in the Berlinische Monatsschrift.
• 1786, 17 August: Frederick the Great dies.
• 1804, 12 February: Kant dies in Königsberg.

Legacy

Kant’s essay became a standard reference point for the whole Enlightenment, read alongside works such as Voltaire’s Candide and Rousseau’s Social Contract. Its call to think for oneself has been quoted by educators, scientists and defenders of free expression, and sapere aude has been adopted as a motto by many schools and institutions.

Twentieth-century philosophers returned to it repeatedly. Michel Foucault wrote an essay with the same title in 1984, two centuries later, treating Kant’s text as the start of a modern tradition of reflecting critically on one’s own time. Debates over Kant’s distinction between public and private reason continue in discussions of free speech and the duties of public officials.

Why it matters

What Is Enlightenment? condensed a broad intellectual movement into a clear challenge: have the courage to use your own reason. By linking enlightenment to freedom of public discussion, Kant set out ideas about autonomy, free expression and critical thinking that remain central to modern democratic culture.