fallacy

fallacy, sophism, sophistry, casuistry are comparable when meaning unsound and misleading reasoning or line of argument. The same distinctions in implications and connotations are distinguishable in the corresponding adjectives fallacious, sophistical, casuistical.

Fallacy and fallacious in specific logical use imply an error or flaw in reasoning that vitiates an entire argument; thus, a syllogism in which one argues from some accidental character as though it were essential and necessary (as, The food you buy, you eat; you buy raw meat; therefore you eat raw meat) contains a fallacy or is fallacious

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the many fallacies that lurk in the generality and equivocal nature of the terms "inadequate representation"— Burke

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In more general use fallacy and fallacious apply to a conception, belief, or theory that is erroneous and logically untenable, whether it has been arrived at by reasoning or by conjecture or has been taken over from others

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the arguments of the Federalist are intended to prove the fallacy of these apprehensions— John Marshall

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the separatist fallacy, the belief that what may be good for any must be good for all— Hobson

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parents . . . console themselves by the American fallacy that one can only be young once— Elizabeth Bowen

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the contention of some that the debt is not serious because we owe it to ourselves is fallacious— Ogg & Ray

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Sophism and sophistry and sophistical imply, as fallacy and fallacious do not necessarily imply, either the intent to mislead or deceive by fallacious arguments or indifference to the correctness of one's reasoning provided one's words carry conviction; the terms, therefore, often connote confusingly subtle, equivocal, or specious reasoning. Sophism, however, applies usually to a specific argument of this character, sophistry often to the type of reasoning employing sophisms

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skilled to plead, with a superficial but plausible set of sophisms, in favor of . . . contempt of virtue— Shelley

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the juggle of sophistry— Coleridge

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this evil is . . . inexcusable by any sophistry that the cleverest landlord can devise— Shaw

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Rousseau does not often indulge in such an unblushing sophism— Babbitt

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the sophistical plea that matter is more important than manner— Montague

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Casuistry and casuistical imply sophistry only in their extended senses. In their basic senses both have reference to the science that deals with cases of conscience, or the determination of what is right and wrong in particular cases where there is justifiable uncertainty

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we now have to lay the foundation of a new casuistry, no longer theological and Christian, but naturalistic and scientific— Ellis

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In their extended use both terms usually imply sophistical and often tortuous reasoning in reference to moral, theological, and legal problems

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those who hold that a lie is always wrong have to supplement this view by a great deal of casuistry— Russell

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casuistical hairsplitting

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