The previous essay left Montaigne defending a book by dismantling the human claim to certainty. This one asks how he does it—and whether he knows what his method will cost.

The harder objection

Sebond's critics fall into two groups. The first questions the need to support faith with human reasoning at all. The second says that Sebond's reasoning is simply not good enough.

Montaigne makes no secret of his answer to the second group. He proposes to take the meagre weapons of reason out of their hands.

Then he asks a question that enlarges the dispute. Do they have better arguments than Sebond? Can a human being, by argument and inference alone, arrive at anything certain?

The issue is no longer whether Sebond's reasons are sound. It is whether human reasoning can stand securely at all.

The difficulty is immediate. Sebond uses human reasoning too. If reasoning cannot reach certainty on its own, his book cannot reach it by that route either. Montaigne has held off the attackers by digging away the ground on which Sebond, in this particular contest, also stands.

A boundary matters here. This is not the same as rejecting Sebond outright. Montaigne is testing what unaided human reason can establish; faith has a separate place in the chapter. The trial is being conducted with human weapons. The question is how far those weapons will take us.

No safe place outside

Later, Montaigne proposes that we place this human being before himself, and his reason before his reason, to see what it has to say.

He supplies the outcome too. The compasses and the person wielding them are both brought to nothing.

It is not only the measuring instrument that fails the test. The measurer goes with it. The person making the argument has reserved no safe patch of ground beyond its reach.

Then he names the price

At this point in the chapter, Montaigne turns from the critics to a woman he is addressing. For her, he says, he has broken his usual practice and written at such length.

What follows is a warning. This last move is an extreme remedy. It is a desperate stroke: you must abandon your own weapons to make your opponent abandon his. Such a secret method should be used sparingly, and held in reserve.

He gives it an even shorter description. You destroy yourself in order to destroy the other person.

Then he advises her to go on defending her Sebond in the ordinary way.

Notice what he does not say. He does not forbid the method. He says that it has a price, and that one should choose the occasion.

You do it too

There is a useful line in an argument: you do it too.

Often it is true, which may leave the other person briefly speechless. But its achievement is limited. It places the speaker back under the standard they have applied to someone else. They cannot stand outside their own rule.

It does not show that the rule is wrong. Someone who is habitually late can still be right that lateness wastes other people's time.

Montaigne's argument is not merely a grander version of you do it too. He is asking whether the instrument used to establish certainty can be trusted in the first place. There is, nevertheless, a shared requirement: you cannot send your opponent into the test and arrange to stay outside it yourself.

An extreme remedy

In the longest chapter of his book, Montaigne presses the claim to human certainty to its limit. He also turns to the woman he is addressing and says: do not make a habit of this. Defend him in the usual way.

A man carries his own method this far and still tells someone close to the argument how expensive it is. This is more than modesty. He knows what using it requires. He knows the price cannot be paid on every occasion.

An extreme remedy is not extreme only because it is powerful. The person who takes it must also endure it.