Six Common Fallacies in Critical Thinking

Fallacious arguments are widespread and can be persuasive in common use. It’s important to understand what fallacies are so that one can recognize them. A fallacy is the use of invalid or faulty reasoning - it’s a systematic error in the construction of an argument.

Assessing the logic of a claim is a process that essentially involves three steps:

  1. the correct formulation of a claim;
  2. the identification of logically relevant and interconnected underlying assumptions that support the claim; and
  3. the validation of the claim.

1. Two of the most common errors in the correct formulation of an argument are false statements or misrepresentations as to the merits of the claim:

1.1 Straw man fallacy:

A straw man fallacy occurs when the challenger replaces an argument with a distorted or exaggerated version, often taken out of context, in an attempt to attack and discredit it. The stronger original argument is substituted by a weaker argument (the "straw man") - a position that the proponent does not really hold. The real harm of this technique – often used on Social Media – is that it distracts attention from the real issue.

For example: “You want to reduce the defense budget? You must hate our military and don’t support our soldiers.”

Another example, a parent tries to convince their child to finish supper. It goes like this: Parent: No dessert until you finish your chicken and vegetables! Child: You only love me when I eat.

1.2 False Dichotomies (either, or):

There are certain categories of arguments where there are legitimately only two options – a true dichotomy. A true dichotomy refers to a set of mutually exclusive choices that cover all options: for example, either a whale is a mammal, or it is not. In contrast, a false dichotomy occurs when the choices are not mutually exclusive or - more commonly - when they do not cover all possibilities. This type of reasoning is erroneous by limiting the options to two when the choice is actually broader. The issue is one of oversimplification.

False dichotomies are often used by politicians or leaders in general to manipulate people into allying with them, they say “You are either with us or against us”. This is a false dichotomy because you could be indifferent, partially with them or partially against them.

2. Two categories of common errors are attributable to the absence of logically relevant and interconnected underlying assumptions that support the claim. The fallacy consists in introducing elements that are superficially similar but irrelevant to the issue at hand, or in focusing all the attention on the speaker rather than on the content.

2.1 Red Herring:

The mechanism of this fallacy is similar to that of the Straw man in that it ultimately distracts from the real issue. The term Red Herring was popularized by an Englishman in the 19th century who told the story of a strongly smelling smoked fish used to divert and distract hounds from chasing a rabbit. A Red Herring fallacy uses irrelevant or unrelated information to distract from the argument at hand. Red Herrings are arguments that may seem relevant to the issue but actually are not. They are often used by people to divert blame away from themselves.

For example: “You bring up gay marriage and claim I’m against it but isn’t it as important to talk about the issue of homeless veterans. Did you know that I volunteer at a local shelter?” This is a Red Herring, because the value of volunteering at a homeless shelter is beyond the point and unrelated to the question of gay marriage.

2.2 Ad Hominem:

Ad Hominem means "against the man" in Latin. This common fallacy refers to a person who substitutes a rebuttal with a personal insult, introducing the false premise that this kind of person cannot offer a valid argument.  The use of an Ad Hominem is commonly known in politics as "mudslinging". Instead of addressing a candidate’s stance on issues or merit as a statesman or stateswoman, an Ad Hominem focuses on personality, wardrobe, style and other aspects that influence popularity but have no bearing on competence.

3. The two most common errors in the validation of reasoning are making claims more credible than they actually are by using a questionable authority or by engaging in questionable comparisons/analogies:

3.1 Questionable Authority:

This logical fallacy of arguing happens when we misuse an authority. Basically, we argue that something is "correct" or "true" because an "expert" in an unrelated area says so. This is commonly used by both advertisers, politicians, or anyone who conveniently steers away from other concrete evidence and relies on their Uncle Joe for the "correct" answers to all controversial issues.

For example: quoting an orthopedist when trying to prove something about psychiatry; his/her expertise is irrelevant in the field of psychiatry.

3.2 Questionable Comparison:

The mechanism of this flawed reasoning is based on the assumption that if two or more things are similar in one respect, they must be alike in other ways when there are otherwise very different things. The question to ask yourself is – is this a fair comparison?

We commonly compare data points of interest to other data numbers we better understand in order to make better sense of it. In business, this is called benchmarking. You can only learn from benchmarks if they possess enough similar traits to the comparison of interest and if the lessons are transferrable.

For example: this spring many news sources reported that the number of people in the US who had died from Covid-19 had surpassed the number of deaths of Americans in the Vietnam, Korean, and Desert Storm wars combined. This comparison seemed to be made to demonstrate the large number of deaths caused by Covid-19, but is it a fair comparison? From a logical standpoint, this seems to be a poor comparison because the number of people at risk of dying in these two scenarios was vastly different (soldiers sent to war versus the whole US population at risk) and the actions that led to or averted deaths in these scenarios were very different. A much better comparison would have been to look at deaths from other diseases that could affect the whole population, such as the flu or cancer.

Among the information received today, try to find one of the six fallacies described above. You will be amazed at the result.

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