The Quotation IndexThe trusted reference for quotations and the sources behind them
Tag Tag Reasoning
The test of a first-rate intelligence is the ability to hold two opposed ideas in the mind at the same time, and still retain the ability to function.
F. Scott Fitzgerald The Crack-Up · 1936

Quotes

“In the development of our understanding of complex phenomena, the most powerful tool available to the human intellect is abstraction. Abstraction arises from a recognition of similarities between certain objects, situations, or processes in the real world, and the decision to concentrate on these similarities, and to ignore for the time being the differences.”

Tony Hoare · Structured Programming, 1972 · Primary source

“So convenient a thing is it to be a reasonable creature, since it enables one to find or make a reason for everything one has a mind to do.”

Benjamin Franklin · The Autobiography of Benjamin Franklin, 1771-1790 · Primary source

“What is the hardest task in the world? To think.”

Ralph Waldo Emerson · Intellect, 1841 · Primary source

“He who thinks little, errs much.”

Leonardo da Vinci · The Notebooks of Leonardo Da Vinci, 1888 · Primary source

“Any one who in discussion relies upon authority uses, not his understanding, but rather his memory.”

Leonardo da Vinci · The Notebooks of Leonardo Da Vinci, 1888 · Primary source

“It was a reaction I learned from my father: have no respect whatsoever for authority; forget who said it and instead look at what he starts with, where he ends up, and ask yourself, Is it reasonable?”

Richard Feynman · What Do You Care What Other People Think?, 1986 · Primary source

“Invert, always invert.”

Carl Jacobi · No reliable source

Related Tags

Judgement 31 Perspective 21 Evidence 19 Understanding 15 Complexity 15 Problem-solving 15 Critical thinking 13 Motivation 11 Reflection 10 Independent thought 8 Memory 7 Independent judgement 7 Self-deception 6 Bias 6 Abstraction 4 Authority 4 Intellectual flexibility 4 Rationalisation 3 Generalisation 2 Thinking 2 Intellectual effort 2 Inversion 1 Mathematical method 1 Error 1 Contradictory ideas 1 Mental resilience 1