The public and private use of reason

In Unit 2 we met Kant’s diagnosis: Unmündigkeit — self-incurred immaturity, the inability to use one’s own understanding without another’s guidance — is the disease, and sapere aude (“dare to know”) is the cure. But a cure needs a mechanism. How, concretely, does a whole people climb out of tutelage? Kant’s answer is a single institutional condition: freedom. And not just any freedom — one very particular kind, which he isolates with a distinction that has confused readers for two centuries.

The distinction is between the public use of one’s reason and the private use of one’s reason. Kant’s claim is stark: the public use of reason must always be free, and it alone can bring enlightenment to humankind; the private use of reason may often be narrowly restricted, without any particular harm to the progress of enlightenment. Everything now depends on what he means by those two words — and he means something deliberately, almost perversely, counter-intuitive.

By the public use of one’s reason Kant means the use a person makes of it as a scholar (als Gelehrter) before the entire reading public — the whole world of readers. When you write, reason, and address humanity at large as one rational being speaking to others, you are making the public use of reason. This is the free, world-directed voice. Cite the source directly: What is Enlightenment?.

By the private use of one’s reason Kant means the use a person makes of it in a particular civil post or office that has been entrusted to them (in einem gewissen ihm anvertrauten bürgerlichen Posten). When you speak in role — as the holder of an office, executing a function you are paid and appointed to perform — that is the private use. And in role, you can be legitimately restricted: the machine of public life needs some parts to obey, or it seizes up.

Now Kant’s three worked examples — the heart of the essay’s politics. Take the military officer. On duty, receiving an order from a superior, the officer must obey; it would be ruinous for a soldier to debate the wisdom of a command in the field. That is the private (role-bound) use of reason, and restricting it does no harm to enlightenment. Yet the same officer, writing as a scholar about defects in military policy and laying his reasoning before the reading public, cannot fairly be forbidden to do so. In role: obey. As a scholar: speak freely.

The citizen and taxes. A citizen cannot refuse to pay a tax lawfully levied on them — indeed, Kant says, impertinent grumbling that obstructs collection may be punished as scandalous. That is the private use: as a cog in the fiscal machine, one pays. But that very same person, as a scholar, may publicly voice their thoughts on the injustice or inexpediency of such taxes to the whole reading world. Paying is obligatory; arguing against the levy in print is free.

The clergyman — Kant’s most delicate case. A pastor is bound, as the appointed officer of their church, to instruct their congregation according to the creed of the church they serve; they teach in the church’s name, on its commission, and to that extent are not free and ought not to be. That is the private use of reason. But — and here is the pivot — as a scholar the same clergyman has complete freedom, indeed a calling, to communicate to the public their carefully examined, well-intentioned thoughts about what is mistaken in that creed, and their proposals for a better ordering of religious matters. As church-officer, bound; as scholar addressing humanity, free.