Errors with staying power. To be a fallacy, someone must fall for it, as Lewis Carroll points out,

Any argument which deceives us, by seeming to prove what it does not really prove, may be called a ‘Fallacy’ (derived from the Latin verb fallo “I deceive”).F1

Both formal and informal logic recognise the existence of fallacies. From the point of view of formal logic, a fallacy is an error which violates the laws of reasoning; it can be demonstrated as an error in many ways—with the use of (for instance) symbols, diagrams, words, maths, computer syntax. These, in the terms of formal logic, are “genuine fallacies”.

Informal logic, on the other hand, recognises many other kinds of fallacies; a number do indeed violate the laws of reasoning (like Begging the Question), but others are more about the equivocal use of language (Devil’s Voice), or humour (Play), or submission to a threat (Big Stick), or distraction (Contrarian Fallacy), or a misconception about the way systems work (Death), or long-held errors about matters of fact (Ignorance). For a whistle-stop tour of such informal fallacies, see “How To Cheat in an Argument”).F2

Informal fallacies can be used for good purposes or bad, but the risk of their causing trouble—especially for those unfamiliar with them—is significant. Studying them helps develop the art of coherent argument, as well as improving awareness of its importance, and assists the diagnosis when a dialogue goes wrong. It may also suggest a cure.F3


Related entries:

Manners, Deceptions.

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David Fleming
Dr David Fleming (2 January 1940 – 29 November 2010) was an economist, historian and writer, based in London. He was among the first to reveal the possibility of peak oil's approach and invented the influential TEQs scheme, designed to address this and climate change. He was also a significant figure in the development of the UK Green Party, the Transition Towns movement and the New Economics Foundation, as well as a Chairman of the Soil Association. His wide-ranging independent analysis culminated in two critically acclaimed books, Lean Logic and Surviving the Future. A film about his perspective and legacy - The Sequel: What Will Follow Our Troubled Civilisation? - was released in 2019, directed by BAFTA-winning director Peter Armstrong. For more information, including on Lean Logic, click the little globe below!

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