Etymology
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fallacy (n.)
late 15c., "deception, false statement," from Latin fallacia "deception, deceit, trick, artifice," abstract noun from fallax (genitive fallacis) "deceptive," from fallere "deceive" (see fail (v.)). Specific sense in logic, "false syllogism, invalid argumentation," dates from 1550s. An earlier form was fallace (c. 1300), from Old French fallace.
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fallacious (adj.)
c. 1500, from fallacy (Latin fallacia) + -ous. Related: Fallaciously; fallaciousness.
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disabuse (v.)

"free from mistake, fallacy, or deception," 1610s, from dis- + abuse (v.). Related: Disabused; disabusing.

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Monte Carlo 

resort town, capital of Monaco, Italian, literally "Charles's Mountain," founded 1866 and named for Charles III of Monaco (1818-1889). The car rally there dates to 1911. The Monte Carlo fallacy (by 1957) was named for the town's famous gambling casinos; it is the fallacy of thinking that the probability of a particular outcome rises with the successive number of opposite outcomes. Contrary to the Monte Carlo fallacy, if the roulette wheel stops on black 99 times in a row, the chances that the 100th spin will be red are still just under 50-50. 

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post hoc 
Latin, "after this." Especially in post hoc, ergo propter hoc, logical fallacy, literally "after this, therefore because of this."
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intentional (adj.)

"done with intention, design, or purpose; intended," 1520s, from intention + -al (1) or else from Medieval Latin intentionalis. Intentional fallacy recorded from 1946. Related: Intentionality.

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sophism (n.)
early 15c., earlier sophime (mid-14c.), "specious but fallacious argument devised for purposes of deceit or to exercise one's ingenuity," from Old French sophime "a fallacy, false argument" (Modern French sophisme), from Latin sophisma, from Greek sophisma "clever device, skillful act, stage-trick," from stem of sophizesthai "become wise" (see sophist).
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equivocation (n.)

late 14c., "the fallacy of using a word in different senses at different stages of the reasoning" (a loan-translation of Greek homonymia, literally "having the same name"), from Old French equivocation, from Late Latin aequivocationem (nominative aequivocatio), noun of action from aequivocus "of identical sound, of equal voice, of equal significance, ambiguous, of like sound," past participle of aequivocare, from aequus "equal" (see equal (adj.)) + vocare "to call," which is related to vox (genitive vocis) "voice" (from PIE root *wekw- "to speak").

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petitio principii 

Latin, from petitio "petition" (see petition (n.)) + genitive of principium (see principle (n.)). It translates Greek to en arkhē aiteisthai "an assumption at the outset."

In logic, the assumption of that which in the beginning was set forth to be proved; begging the question: a fallacy or fault of reasoning belonging to argumentations whose conclusions really follow from their premises, either necessarily or with the degree of probability pretended, the fault consisting in the assumption of a premise which no person holding the antagonistic views will admit. [Century Dictionary]
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pathetic (adj.)

1590s, "affecting the emotions or affections, moving, stirring" (now obsolete in this broad sense), from French pathétique "moving, stirring, affecting" (16c.), from Late Latin patheticus, from Greek pathetikos "subject to feeling, sensitive, capable of emotion," from pathetos "liable to suffer," verbal adjective of pathein "to suffer" (from PIE root *kwent(h)- "to suffer").

The specific meaning "arousing pity, sorrow, or grief" or other tender feelings is from 1737. The colloquial sense of "so miserable as to be ridiculous" is attested by 1937. Related: Pathetical (1570s); pathetically. The pathetic fallacy (1856, first used by Ruskin) is the attribution of human qualities to inanimate objects.

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