The fox knows many things but the hedgehog knows one big thing.
Aesop’s Fable: “The Fox and the Hedgehog.”
An enfeebled fox is plagued by flies, ticks or mosquitoes, of which a hedgehog offers to rid her. The fox refuses such help on the grounds that the insects have already gorged themselves on her blood and hardly trouble her now, but they would inevitably be succeeded by new swarms if removed. The fable is mentioned by Aristotle in his work on Rhetoric (II.20) as an example of Aesop’s way of teaching a political lesson through a humorous example. The context in this case was said to be the trial of a demagogue; Aesop pointed out that, since self-interested politicians are a necessary evil, to replace one who has already exploited the state with others who have yet to satisfy their greed would only make the situation worse. 1
The reason for the fox’s enfeebled state is that, while crossing a river, she has been swept into the mud on the other bank and cannot free herself. These circumstances are repeated in the neo-Latin verse of Gabriele Faerno’s fable collection (1563), which closes on the sentiment
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Who seeks a ruler to reverse Calls in another that is worse.
Isaiah Berlin’s Essay: “The Hedgehog and the Fox”
Isaiah divide writers and thinkers into two categories: hedgehogs, who view the world through the lens of a single defining idea (examples given include Plato, Lucretius, Blaise Pascal, Marcel Proust and Fernand Braudel), and foxes, who draw on a wide variety of experiences and for whom the world cannot be boiled down to a single idea (examples given include Aristotle, Desiderius Erasmus, Johann Wolfgang Goethe).2
Philip Tetlock summarized substantial research claiming that most experts and well-paid pundits think like hedgehogs with one big idea; on average they make poor forecasts. Meanwhile, people who draw information from a large variety of often-conflicted sources, like foxes, make better forecasts.