Fallacy (logic)

A fallacy is an error in reasoning. Fallacies are most often discussed within a subset of philosophy known as logic. Fallacies can be faults in logical reasoning, application of soundness, or application of validity, or at the extreme, fallacies can be a disregard for reason and logic all together. Fallacies can either be formal, informal, or both. Formal fallacies entail a flaw in the logical reasoning of an argument. Informal fallacies entail a flaw in the premises of the argument. It is also possible for a fallacy to contain elements of a formal fallacy and an informal fallacy, where the logic and premises of an argument are flawed.

Background

Formal fallacies include non sequiturs, propositional fallacies, qualification fallacies, and flaws in the argument itself, also known as syllogistic fallacies. Informal fallacies do not fall under a set stratification and are loosely tied together via the flaw inherent in their premises.

Non sequiturs are arguments where the conclusion does not follow from its premises. In the case of a non sequitur, the conclusion may be true, but it will not be derived from or proven by the argument. Examples of non sequitur arguments include affirming the consequent, denying the antecedent, affirming a disjunct, denying a conjunct, and ignorance of the undistributed middle term.

Propositional fallacies are formal fallacies that may also be classified as non sequiturs. Propositional fallacies revolve around mistakes in logic concerning conjunctive or disjunctive proposition connectors, such as and, or, nor, not, if, and if and only if. Affirming the consequent, denying the antecedent, affirming a disjunct, and denying a conjunct are all formal propositional fallacies. Many propositional fallacies are also syllogistic fallacies.

Qualification fallacies are formal fallacies that assume the existence of a group based on a feature of the group. Qualification fallacies also include an individual not making the distinction between all, some, and none, when qualifying an action or trait in regard to an argument. A further example of a qualification fallacy is the vacuous truth, which states that all members of a group share a common feature, but no members of the group exist. An example of an existence qualification fallacy would be "All dragons breathe fire"; however, such a claim does not denote that dragons are a mythical creature.

Informal fallacies are used more in rhetoric. Informal fallacies often disregard the rules and order of logic and reason and attempt to use intuition or an appeal to a person’s desires in order to win them over to a certain point of view.

Topic Today

Informal fallacies are commonly, possibly inadvertently, used by public speakers such as lawyers, politicians, spokespersons, and sales professionals. These fallacies are used in order to win a person over to a particular point of view or to prevent someone from fully grasping an issue.

An "appeal to the stone" is a fallacy which dismisses a claim as nonsense without addressing the value or pertinent information in the claim. This is closely related to ad hominin attacks, or red herring fallacies. These types of arguments are designed to push aside an issue that may be detrimental to one’s positon without just consideration of its merits.

Appeals to emotion are used to inflame the base desires of an individual, such that the person does not consider the merits of the claim, only the emotional outcome. Adolf Hitler (1889–1945) used appeals to emotion in order to obtain consent and popular support for the Third Reich. By arguing that Germany was unfairly treated after losing the First World War, Hitler appealed to the emotions of the German people, which he used to further his political and military goals.

Appeal to novelty is used in advertisements. This fallacy claims that something is better merely because it is new. This is used to entice a person to commit to an action without consideration of whether or not the product is of any increased value or is merely a new release of an already adequate product.

An appeal to authority is a fallacy that uses a person’s rank, title, position, or assumed knowledge to justify a claim. Under this case, the person hopes that his position is sufficient to move people to his claims, regardless of the evidence for or against it. Closely related to an appeal to authority is the appeal to accomplishment, where the past accomplishments of the individual are used to support a claim, rather than the individual merits of the claim.

Circular reasoning fallacies entail when the premises of an argument are used as the conclusion of an argument. Under a case of circular reasoning, there is no independence of the premise or claim and the conclusion. Closely related to circular reasoning is "begging the question," where the conclusion is assumed in one of the premises, and defining a word, term, or concept with a variation of itself. Circular reasoning is sometimes called assuming the conclusion.

A false dilemma fallacy occurs when a speaker presents only two options as being valid or available when in reality there are multiple courses of action possible. Similar to this is when two courses of action are proposed, but both courses are actually the same thing. An example of the false dilemma fallacy occurs with describing tax analysis of a population. Under this fallacy, a population is assumed either to be wealthy, and therefore have money to be taxed, or to be frugal, and therefore have saved enough money to warrant being taxed. The fallacy does not leave open the possibility that the population may be in such destitution that it cannot afford to pay any taxes.

The nirvana fallacy occurs when solutions are rejected because the outcome provided is not perfect. The nirvana fallacy is commonly seen in healthcare politics and in complex legislation. Under healthcare politics, groups of politicians will reject a proposal because the proposal does not account for all possibilities that may occur. Similarly, with complex legislation, bills may be vetoed because they do not account for all outcomes that may result.

Bibliography

Bennet, Bo. Logically Fallacious: The Ultimate Collection of Over 300 Logical Fallacies. Sudbury: eBookit, 2012. Print.

Engle, S. Morris. Fallacies and Pitfalls in Language: The Language Trap. Mineola: Dover, 1994. Print.

Hurley, Patrick J. A Concise Introduction to Logic. Boston: Wadsworth Cengage Learning, 2014. Print.

LePore, Ernest, and Sam Cumming. Meaning and Argument: An Introduction to Logic through Language. Hoboken: Wiley-Blackwell, 2012. Print.

Paul, Richard, and Linda Elder. The Thinker’s Guide to Fallacies: The Art of Mental Trickery. Washington, DC: Foundation for Critical Thinking, 2008. Print.

Pirie, Madsen. How to Win Every Argument: The Use and Abuse of Logic. London: Bloomsbury Academic, 2015. Print.

Sinnott-Armstrong, Walter, and Robert Fogelin. Understanding Arguments: An Introduction to Informal Logic. Boston: Wadsworth Cengage Learning, 2010. Print.

Whyte, Jamie. Crimes Against Logic: Exposing the Bogus Arguments of Politicians, Priests, Journalists, and Other Serial Offenders. New York: McGraw-Hill, 2004. Print.