Did Voltaire really say "Common sense is not so common"?

Close, but no. Voltaire wrote that common sense is "fort rare," which means very rare. The tidy English one-liner going around is a reworded version that appears in no edition of his work.

The version going around

You have seen it on posters, mugs, and quote sites:

"Common sense is not so common." Voltaire, 1764.

It sounds like him. It is short, dry, and a little superior. That is exactly why it spread. But it is not what he wrote.

The verdict

The real line lives in Voltaire's Dictionnaire philosophique, in the entry "Sens commun." The dictionary first appeared in 1764, and the "Sens commun" entry shows up in the expanded editions that followed. In the sixth edition of 1767, the sentence reads:

"On dit quelquefois, le sens commun est fort rare"

In plain English: "People sometimes say, common sense is very rare." Two things get lost in the popular version. First, "fort rare" means very rare, a stronger claim than "not so common." Second, Voltaire is not even coining the line. He opens with "on dit quelquefois," people sometimes say. He is quoting a common saying so he can examine it, and the thought itself goes back to the Roman poet Juvenal, who wrote that common sense is rare at the heights of fortune.

So where did "not so common" come from? No edition of the Dictionnaire philosophique contains it, in French or in the early English translations. It reads like an aggregator-era smoothing of the real line, the kind of edit that makes a quote easier to print on a mug. Versions of it also float around under Mark Twain's and Will Rogers's names, which is usually a sign that a quote has drifted loose from any source at all.

To be fair to the internet, this one is a near miss, not a fabrication. The thought is genuinely Voltaire's material. The words are not.

What Voltaire actually wrote

The French, from the Dictionnaire philosophique portatif, entry "Sens commun," sixth edition, 1767:

"On dit quelquefois, le sens commun est fort rare"

A plain rendering: "People sometimes say, common sense is very rare."

H.I. Woolf's 1924 public-domain translation gives the same phrase as "Common sense is very rare." Voltaire then explains what the saying means: in many people, reason gets stopped in its tracks by prejudice, so a man who judges soundly in one matter will be badly wrong in another. That is the actual argument. Not that most people are dim, but that everyone's good judgment has blind spots.

Why we check

Every quote in Lumoro's morning texts gets verified against a primary source before it sends. Not a quote site, the actual book. This one earned a correction, not a spot in the rotation. If a line cannot survive a trip back to the page it supposedly came from, it does not go out under someone's name.