A sophism , or argument with fallacious logic , is a reasoning which appears rigorous and logical, but which actually is not Valide (not to be confused with true ). Sophism rests on the engine of the Syllogisme, or the Enthymème (with an eluded argument). The adjective fallacious indicates what is misleading or untrue. The Logique indicates in Rhétorique art to build a coherent speech.

Certain sophisms are faulty because of an insufficiency of their Prémisses, others because of the absence of Pertinence of the premises opposite the conclusion.

Fallacious logics were explained and peeled at teaching ends: for example, during ignited discussions, it is useful to differentiate what holds of logic, of what does not hold any. A fallacious logic is a “false” logic, independently of the veracity of the postulates and conclusion. In fact the latter result directly from the work Art to be right always (1830 - 1831) which is a work of Schopenhauer, and the arguments original were wide thereafter.

It is difficult to detect fallacious logics, and they are rather often effective to convince. The purpose of this article is initially to define what are fallacious arguments, and then to present an not-exhaustive list of the latter which are traditionally named in Latin.

Aristote wrote the Sophistical Refutations , where it exposes different the sophisms and the means of refuting them.

Examples

Paradox of the emmental:

  1. Plus there is emmental, more there are holes.

  2. Plus there are holes, less there is emmental.
  3. Donc more there is emmental, less there is emmental

  1. a cheap horse is rare,

  2. All that is rare is expensive,
  3. Donc a cheap horse is expensive.

  1. No cat has eight tails,

  2. a cat has a tail moreover than no cat,
  3. Donc a cat-o'-nine-tails.

Classification of Millet

John Stuart Mill, in her work System of deductive and inductive logic (1843), studies sophisms. He proposes a classification, which is made up in four groups:

  1. “Of sophisms of simple inspection , or sophisms a priori”. They are “the cases where there is no drawn conclusion, the proposal being accepted, not as proven, but like not needing proof, like obvious truth in oneself, or at least like so great intrinsic probability, which the external proof, although insufficient by itself, is enough like additive to the former presumption”.
  2. “sophisms of observation ”. In fact sophisms consist of a vicious mode to proceed in the operation of the proof. And like a proof, in all its extent, embraces one or more or the totality of three processes, the observation, generalization, and the deduction, it is necessary to examine the errors which can be made in these three operations. A sophism by observation can consist of an error of “nonobservance” (negligence of the particular facts that it was necessary to notice), or “badly-observation” (“when the fact or the phenomenon, instead of being recognized for what it is actually, is taken for something other”).
  3. “sophisms of generalization ”. this class is considered, by Mill, like the most extended from all, by embracing a greater number and a larger variety “of vicious inférences”. So that an error of generalization is sophistical, specifies Mill, “it is necessary that it is the consequence of a principle; it must come from some false general design of the inductive process; the legitimate mode to draw the conclusions of the observation and the experiments must be basically badly included/understood”.
  4. “sophisms by confusion ”. This last classification of sophisms of Millet, gathers “all those which have their source, not so much in a false evaluation of the value of a proof, which in the vague, unspecified and floating design of what is the proof”. “At the head of these sophisms these multitudes of vicious reasoning are offered resulting from the ambiguity of the terms, when of a thing which is true in the particular direction of a word one argues as if it were true in another direction”.

List fallacious arguments

Sophisms whose Prémisse S are not relevant with the validity of the Conclusion.

  • Argumentum AD hominem or attacks personal is formulated against the person who supports a Thèse, and not against the thesis itself, it includes/understands ad personam argumentum, AD hominem circumstantiæ and quoque AD hominem you.

  • argumentum AD verecundiam also called the chief always has reason , or argument of authority .

  • Argumentum AD consequentiam

    • Call to terror “If you maintain your point of view, there will be consequences …”
    • Appel with the flattery “a man as you cannot defend such a kind of position”
    • Argumentum AD populum (also called the reason of the majority). Ex: God must exist since the majority of the human S believes in it since millenia . Alternative: the France represents less than 1% of the world population and cannot thus have any significant Rôle (the Athens of Périclès represented much less than 1% of the population of its time, and its model influences us still today; Sparte, much more powerful at the same time, did not leave of durable cultural trace.)
    • Argumentum AD misericordiam
    • Appel with ridiculous the
    • Argumentum AD odium
    • Two forgeries make a truth
    • the Raison of the finer feelingss

  • Argumentum AD novitatem

  • Argumentum AD antiquitatem (also called everyone made like that , sales point of the marks )
  • Argument by the faith “It is inevitably true, since it is written in such or such book crowned” .
  • Argumentum AD ignorantiam (ignorance) e.g.: “I cannot explain what this witness saw in the sky, therefore that must be an extraterrestrial spaceship visiting our planet” .
  • Argumentum has silentio
  • Argumentum AD baculum (also called the reason of most extremely the )
  • Argumentum AD crumenam (also called the the reason of richest the ) “It is not this dead loss not even fixed with the STF which will give me lessons to lead my life” (see Ésope, Épictète…).
  • Argumentum AD lazarum (also called the the reason of poorest the ) “the working class fights with reality the every day and is alone to know the reality of the country. Dictatorship of the proletariat is thus the only solution”
  • Argumentum AD nauseam (also invited to have reason by fixed price ) “did you read the 38000 references that I have just quoted you? Not? Eh well I consider whereas you do not have anything to bring to this debate”
  • Petitio principii (also called circular argument ): “My brother does not like spinaches, and they is happy for my brother, because if he liked them, he would eat some; however it cannot support them” . Alternative: “the poisonous snakes are useful, because without them one could not manufacture the serum immunizing against their venom” .

  • Rupture of the correlation including:

    • Plurium interrogationum (also invited to multiply or complicate the questions)
    • False choice (also called white or black ): “the tidal and geothermal energies are clean, therefore ecologically acceptable; if they are ecologically acceptable, they are thus inevitably renewable . If you dispute this conclusion, you are a partisan of the nuclear lobby”
    • Fausse objection to avoid evoking a true reason: " it is too cher" , or " It is necessary that I speak about it with my femme" , not to say " I have only to make your camelote and you seriously begin with me ennuyer"
    • concentration of the argumentatoire on part of the arguments justifying the standpoint
    • Refusal of the correlation (attention: a correlation does not imply necessarily a Causalité. Thus, the sales of toothpaste are correlated with the sales of condoms; those of Coca-Cola to the sunglasses; the sales of whiskey in Scotland are correlated there with the income of the pastors, and that does not mean that the pastors drink the product of the searches. That states simply that when their sales are good, the Scot have the means of giving a little more to their pastors).
    • To remove the correlation

  • Équivocation

  • Confusion enters the All and the part

    • Prendre the part for the whole: “X voted Machin, Machin is for such reform, therefore X is in favor of this reform”.
    • To divide
excessively

  • Generalization S invalids:

    • sample nonrepresentative “Since my compartment of train, I could note on a sample of 70 crossings level that all without exception have their closed barriers ”.
    • hasty Généralisation (also called hasty deduction , lack of representativeness of the sample ) “ the English is trilingual: yes, I met English who spoke three languages ”
    • excessive Généralisation, also named Dicto simpliciter
    • statistical Manipulation “This test of disease X is reliable to 99%, it appears positive for you, therefore you have disease X” (in fact, if disease X touches a person on 100.000, reliable test a “with 99%” will give 1000 positive where there is only one true patient, and thus a positive test leaves 99,9% more of chance not to have the disease in question).

  • Handling of the probabilities: “Launch three parts: two are inevitably same side, either pile, or face. The third has a chance on two to be also on this side; thus there is a chance on two that the parts are all the three on the same side”

  • the Dishonor by association/the Honor by association: “You are vegetarian? Hold, like this bastard of Lormier! It should not be a chance” . “I am not an imbecile, since I am customs officer” .

  • Ignoratio elenchi (also called excessive conclusion )

  • the Postulate indémontrable

  • Argumentum AD temperantiam (also called the happy medium)

  • the Reason by theatricalness

  • Réductionnisme : “the man is made of material components governed by causality, therefore the only effective way to analyze the human actions consists in being based on causality” (in fact, one obtains models increasingly simpler, and usable, while being based on the contrary on the concepts of Motivation and But)

  • the Reason of Nature or genetics (which mistakes the cause or the origin of a thing for the gasoline or the thing itself) “the Amour, because it rises from the sexual instinct , is not other than the desire to copulate. ”

  • Negation of the proof

  • Not sequitur: (which does not follow the premises)

    • Affirmation of the consequence. Ex: today it makes beautiful, therefore it will rain tomorrow.
    • Refusal of the antecedents

  • No Scottish good

  • the Reason of the emotions

  • the perfect Solution

  • To poison the well (or the Scorched earth policy )

  • Non caused pro caused including:

    • Post hoc, ergo propter hoc (also invited to confuse synchronicity and causality ) “I drank a herb tea, thanks to that my cold disappeared the following day. ”
    • excessive Simplification of causality
    • the excessive Bringings together
    • combination of facts without direct links (Amalgam)
    • Inversion of causality

  • the red Rag

  • the Relativisme

  • the man of straw

  • Syllogisme invalidates (see also Paradoxes)

    • Affirmation of a disjunction
    • excessive Affirmation of the existence of a term
    • Quaternio terminorum
    • Non-distributivité of the pivot
    • Non-distributivité of the major term
    • Non-distributivité of the minor term

  • False dilemma: “Jupiter is a Sphère gas or solid. However, Jupiter is not solid, therefore it is gas. ”

  • Fausse correlation (often justified by a priori that one has on the subject) “100% of the cancer patients ate fruits at least once in their life; consequently the fruits are carcinogenic. ”

  • Sophisms of ambiguity

    • Division: “the American Armée is powerful, therefore this American Soldat must be powerful. ”

  • Sophism of composition: To believe that what is true for the whole is true for the parts or, conversely, that what is true for one of the parts also applies to the others.

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