Definition is a useful way of making it clear what you are talking about. The problem starts, however, when it is supposed that the word or phrase in question has one intrinsically right meaning; the problem gets worse when it is argued that everyone should accept that meaning, and it reaches its nadir when it is combined with bivalence—a refusal to recognise any grey areas. Example: the Fallacy of Definition occurs when a person asserts that an embryo, however soon after conception, is a human, and so qualifies for all the rights that might be claimed by a citizen. The response may be to argue, in contrast, that the embryo does not actually become human until it is two months gone, or six months gone, or until it is born, or even later. There is no way of resolving such a debate; all participants are a little bit right, including those who would go further still and say that a person is not “fully human” until he or she has passed various ritual rites of passage and is an established, socially solvent member of society. And that, furthermore, for some traditional societies this does not occur until the age of 40.

The solution to this problem is to reverse the direction of the definition. Do not argue from left to right—saying, “‘Human’ means [quality ABC]”—a description which is certain to be as murderous to innocence and observation as Bitzer’s definition of a horse in Dickens’ Hard Times:

Quadruped. Graminivorous. Forty teeth, namely twenty-four grinders, four eye-teeth, and twelve incisors. Sheds coat in the spring; in marshy countries, sheds hoofs, too. Hoofs hard, but requiring to be shod with iron. Age known by marks in mouth.D10

Instead, argue from right to left, as in: “I am referring, in this particular conversation, to these particular qualities (ABC described at length, perhaps), and I am labelling them ‘human’. There are certainly other qualities which could be labelled human, by other people in other contexts, but this is what the label means when I use it today.”D11

The Fallacy of Definition is one of the most insidious of all logical errors; it is the source for furious entrenched debate, for breakdowns in communication, for fanaticism, for war. It is possible to solve if and only if the change in the direction of definition—remaining within the reasonable world of right-to-left labelling, rather than left-to-right definition—is understood.


Related entries:

Fallacies, Conversation, Wicked Problems, Good Faith, False Opposite.

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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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