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Cognitive dissonance: Aesop , of course. But it looks even more ancient, with Ahiqar of Nineveh. Also in La Fontaine.
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Loss aversion: Segnius homines bona quam mala sentiunt in Livy’s Annals (XXX, 21) (Men feel the good less intensely than the bad). Nearly all the letters of Seneca
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Negative advice: Nimium boni est, cui hinil est mali Ennius , via Cicero
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Madness of Crowds: Nietzsche: Madness is rare in individuals, but in groups, parties, nations, it is the rule (this counts as ancient wisdom since Nietzsche was a classicist; I’ve seen many such references in Plato).
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Antifragility Cicero (Disp Tusc,II, 22) When our souls are mollified, a bee can sting — See also Machiavelli and Rousseau.
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The Paradox of Progress/Choice (Lucretius): there is a familiar story of a New York banker vacationing in Greece, who, from talking to a fisherman and scrutinizing the fisherman’s business, comes up for a scheme to help the fisherman make it a big business. The fisherman asked him what the benefits were; the banker answered that he could make a pile of money in NY and come back vacation in Greece; something that seemed ludicrous to the fisherman who was already there doing the kind of things bankers do when they go on vacation in Greece. The story was very well known in antiquity, under a more elegant form, as retold by Montaigne I, 42: (my transl.) when King Pyrrhus tried to cross into Italy, Cynéas, his wise adviser, tried to make him feel the vanity of such action. “To what end are you going into such enterprise?”, he asked. Pyrrhus answered:” to make myself the master of Italy”. Cynéas: “ and so?”. Pyrrhus: “to get to Gaul, then Spain”. Cynéas: “Then?” Pyrrhus: “ To conquer Africa, then … come rest at ease”. Cynéas:” but you are already there; why take more risks”? Montaigne then cites the well-known Lucretius (V, 1431) on how human nature knows no upper bound, as if to punish itself.
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Overconfidence: Fiducia pecunias amici “I lost money because of my excessive confidence”, Erasmus citing Theognis, Epicharmus