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A ‘’’Fallacy’’’ is a failure to apply logic to a line of reasoning that renders an argument invalid. Although the word derives from the Latin word fallere, meaning “to deceive”, a person making a fallacy is usually doing so unintentionally, rather than to deliberately communicate a false concept and an individual may hold false beliefs based on fallacious thought processes. The ability to recognize a variety of different forms of fallacy can be useful when analyzing arguments made by others and help avoid making logical errors when forming one’s own beliefs.

The structure of a logical argument should follow a certain basic structure. They begin with one or more premises, which act as the arguments starting point and then by applying principles of logic come to a valid conclusion.

If A = B and B = C then we can conclude A=C.

It is the failure to apply logic rigorously that leads to fallacious arguments.


There are dozens of different forms of fallacy some of the most common include:-

Ad hominem - where the character of the individual making the opposing argument is attacked, rather than the argument itself. e.g “He’s old, fat and bald. There’s no way he would make a good President.”

False dilemma - where the argument proposes only a limited number of possible choices, when a variety of other options may be available. e.g “All people who commit murder should be executed, otherwise once they are released from prison they will murder again.”

Post hoc ergo propter hoc - asserting that because event B followed event A, event A caused event B. “My team won after I wore my new shirt, therefore my new shirt is a lucky shirt.”

Straw man - where an argument takes the form of a deliberately weak or inaccurate description of the counter-argument rendering it easy to “burn down”. e.g “All modern artists do is slap a bit of paint randomly on the canvas without any skill or understanding, if that is art then my three-year old must be genius.”

An appeal to Authority - where an attempt to bolster an argument is made by using well known figure. e.g “We should not go to war with that country because Bono doesn’t want us to.”

False Accusations of Fallaciousness

Matters are further complicated by arguing parties incorrectly claiming that an assertion is false due to a fallacy. For example, if one party was to declare “Albert Einstein has claimed that time and space are relative qualities of the Universe.”, another party might responded by saying that this is an ‘’’argument from authority’’’. However, Albert Einstein’s claims are based on highly detailed mathematical models that identify him as an expert in this field of inquiry, rather than a casual observer.

Equally, if somebody was to make the ad hominem attack “That guy can’t play for the Lakers, he’s only 3 feet tall!”, it would be a valid point as the characteristics of the individual do have a bearing on his ability to play basketball.

Whilst it is possible to overcome these issues by clarifying ones point e.g "Einstein's equations demonstrate that time and space are relative qualities of the Universe" or "He's only 3 feet tall which will make it much harder for him to score" - the necessity to valid each and every aspect of every premise would ultimately mean every argument would have to regress into explaining all aspects of the entire Universe. So certain commonsense, shared assumptions do need to be made in order to communicate an idea.

However it remains important to consider the possibility that under certain circumstances the structure of an argument may take the form of a recognized fallacy, but under closer examination may be perfectly valid.

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