It Is Not Enough To Have

From Part I of the Discourse on the Method (1637). René Descartes opens by observing that good sense (le bon sens, what he calls "reason") is the most evenly distributed thing in the world — everyone thinks they have enough of it. But he immediately adds this qualification: having reason is not enough; using it correctly, by means of good method, is what matters. The Discourse was written precisely to offer that method — the four rules of Cartesian method — to any reader willing to apply it. The remark is characteristic of Descartes's democratic faith that reason, properly disciplined, is available to all.