The Etymological Fallacy

Alias: Abuse of Etymology

Taxonomy: Logical Fallacy > Informal Fallacy > Red Herring > Genetic Fallacy > Etymological Fallacy


Formal logic fails us because of its assumptions. The postulates from which the mechanism springs are normally abstractions of a high order, words rather than things. The finest of automobiles will not run on a road of air; it must have solid ground under the wheels. The Greeks, with their assumption that words were real things, naturally enough soared into rarefied regions. Human thinking has been short of oxygen ever since. … "Logos" is Greek for "word"; "logic" is the manipulation of words.

Source: Stuart Chase, The Tyranny of Words (1938), Chapter 13, p. 226.



The etymology of a word is an account of its historical derivation from older words often from a different language. An older, usually archaic, word from which a current word is historically derived is called its "etymon". The term "etymological fallacy" is applied to two types of error:

  1. Semantic: The etymological fallacy as a semantic error is the mistake of confusing the current meaning of a word with the meaning of one of its etymons, or of considering the meaning of the etymon to be the "real" or "true" meaning of the current word. If one's goal is to communicate, then the "real" or "true" meaning of a word is its current meaning. Since the meanings of words change over time, often considerably, the meaning of an etymon may be very different from the current meaning of the word derived from it. The fact that a word historically derives from an etymon may be interesting, but it cannot tell us the current meaning of the word.

    For instance, the English word "decimate" means "to destroy a large portion of", but is derived from a Latin word having to do with a tenth of something―see the Source, below, for more on its etymology. Some people who know this insist that "decimate", therefore, means to destroy exactly one-tenth, rather than a large part, and may claim that as its "real" or "true" meaning. However, current English is not Latin.

    Source: Ammon Shea, "Does ‘decimate’ really mean ‘destroy one tenth’?", Oxford Dictionaries, 9/10/2012

  2. Logical: The etymological fallacy as a logical mistake results when one reasons about the etymon as if the conclusion applied to the current word. This is a logical error similar to equivocation, which involves confusing two meanings of the same word; but it differs from equivocation in that the etymological fallacy involves the meanings of two different words, though those words are historically connected.


Robert J. Gula, Nonsense: A Handbook of Logical Fallacies (2002), pp. 48 & 161.


The Etymological Fallacy, Fallacy Files Weblog, 6/12/2006

Analysis of the Example:

In the chapter from which this passage comes, Chase is arguing that formal logic is of little or no value because it involves manipulating words unconnected with reality. The passage commits a fallacy and sets up a logical boobytrap:

  1. The Greek word "logos" is actually highly ambiguous, having the following meanings in addition to "word": speech, argument, explanation, principle, reason, among others. But Chase mentions only one of these meanings, namely, the one which supports his argument, rather than others which undermine it―such as "argument" and "reason", which have an obvious bearing on the meaning of the English word "logic". However, assuming that "logos" really only meant "word", would that support his claim that formal logic is simply the manipulation of words? The suffix "-logy" which occurs in such English words as "biology", "psychology", and even "etymology", has the same source as "logic". Does this mean that every science ending in that suffix is really just words about its subject matter, unconnected to reality? Of course not. Just as "biology" came to mean the science of life, so "logic" has come to mean the scientific study of reasoning. Thus, Chase has fallaciously appealed to etymology to support his conclusion.
  2. Chase's analogy comparing formal logic to an automobile is very weak; hadn't he ever heard of airplanes? An alternative analogy would compare formal logic to a plane which can travel much faster than a car by lifting off of the ground and soaring into the atmosphere of abstraction. Of course, there may still be a danger of flying so high that the air becomes too thin, but what is Chase's evidence that this has happened to formal logic? Perhaps the analogy as Chase gives it should be taken only as a colorful illustration of his point, rather than as a reason in its favor, so that it doesn't constitute a fallacious analogy. However, it is at least a boobytrap that might trip up a naive or unimaginative reasoner.

Source: G. B. Kerferd, "Logos" in The Encyclopedia of Philosophy, Paul Edwards, Editor in Chief (1972), Volume 5, pp. 83-84.

Acknowledgments: Thanks to Topher Cooper for suggesting the fallacy, and to Emil William Kirkegaard for pointing out an error in the analysis of the example.