In a footnote to The Revolt of the Masses (1930), Ortega y Gasset asked why no one had, to his knowledge, written an essay on stupidity (tonteria; p. 106).

STPIDITY: Stupidity is the quality or condition of being stupid, or lacking intelligence, as opposed to being merely ignorant or uneducated. This quality can be attributed to both an individual (e.g. Penny Person is stupid) or a person’s actions, words or beliefs (e.g., Penny Person’s policies are stupid). The term can thus also refer to poor use of judgement, or insensitivity to nuances in a person who is otherwise intelligent. The determination of who is stupid is relatively difficult, despite attempts to measure intelligence (and thus stupidity) such as IQ tests. The adjective is also used as a general pejorative (e.g. I didn’t borrow your stupid cap - go look for it yourself).