The Greek in Luke 11:40 that is translated as «(you) foolish people» or «(you) foolish ones» is (back-) translated in a number of ways:

• San Blas Kuna: «people having a dark liver» («incapable of intelligent, thoughtful behavior») (See Seat of the Mind for traditional views of «ways of knowing, thinking, and feeling.»)
• Ekari: «thought not (having) people»
• Kituba, Sinhala, Marathi, Javanese: «people without sense/understanding/intelligence»
• Batak Toba: «those short-of-mind» («mostly referring to stupidity or ignorance in general»)
• Zarma: a word indicating a person who refuses to use the intelligence he has
• Chichewa, Yao: expressions implying intractability and willful opposition to common interests or commonly accepted ideas (source for this and above: Reiling / Swellengrebel)
• Mairasi: «(you are) beeswax» (source: Enggavoter 2004)

See also insane / fool.