CLITANDRE: A learned fool is more foolish than an ignorant fool.

[Un sot savant est sot plus qu’un sot ignorant.]

Molière (1622-1673) French playwright, actor [stage name for Jean-Baptiste Poquelin]

Les Femmes Savantes [The Learned Ladies], Act 4, sc. 3 (1692) [tr. Van Laun (1876)]
    (Source)

(Source (French)). Other translations:

A learned Fool is more foolish than an ignorant Fool.
[tr. Clitandre (1739)]

A learned fool is more of a fool than an ignorant one.
[tr. Wall (1879), The Learned Women]

A learned fool is more foolish than an ignorant one.
[tr. Matthew (1890), The Blue-Stockings]

The learned fool is a far greater fool than the fool of ignorance.
[tr. Wormeley (1895), The Female Pedants]

A learned fool is a bigger fool than an ignorant one.
[tr. Waller (1903)]

There's no fool like a learned fool.
[tr. Page (1908)]

A learned fool is more foolish than an ignorant fool.
[tr. Marks (2018)]