Logical Fallacies

Logical Fallacies :

Are common errors in reasoning that will undermine the logic of your argument. Fallacies can be either illegitimate arguments or irrelevant points, and are often identified because they lack evidence that supports their claim. Avoid these common fallacies in your own arguments and watch for them in the arguments of others.

Ad Hominem

Slippery Slope

Searching for Perfect Solution

Ad Populum

Appeal to Questionable Authority

Appeals to Emotions

Straw Person

Either-Or (or False Dilemma)

Wishful Thinking

Explaining by Naming

Glittering Generality

Red Herring

Begging the Question

Some Logical Fallacy Examples

Summary:

This resource covers using logic within writing—logical vocabulary, logical fallacies, and other types of logos-based reasoning.

Fallacies are common errors in reasoning that will undermine the logic of your argument. Fallacies can be either illegitimate arguments or irrelevant points, and are often identified because they lack evidence that supports their claim. Avoid these common fallacies in your own arguments and watch for them in the arguments of others.

Contributors:Ryan Weber, Allen Brizee Last Edited: 2013-03-11 10:08:50

Slippery Slope:
This is a conclusion based on the premise that if A happens, then eventually through a series of small steps, through B, C,..., X, Y, Z will happen, too, basically equating A and Z. So, if we don't want Z to occur, A must not be allowed to occur either. Example:

If we ban Hummers because they are bad for the environment eventually the government will ban all cars, so we should not ban Hummers.

In this example, the author is equating banning Hummers with banning all cars, which is not the same thing.

Begging the Claim:
The conclusion that the writer should prove is validated within the claim. Example:

Filthy and polluting coal should be banned.

Arguing that coal pollutes the earth and thus should be banned would be logical. But the very conclusion that should be proved, that coal causes enough pollution to warrant banning its use, is already assumed in the claim by referring to it as "filthy and polluting."

Either/Or:
This is a conclusion that oversimplifies the argument by reducing it to only two sides or choices. Example:

We can either stop using cars or destroy the earth.

In this example, the two choices are presented as the only options, yet the author ignores a range of choices in between such as developing cleaner technology, car-sharing systems for necessities and emergencies, or better community planning to discourage daily driving.

Ad hominem:
This is an attack on the character of a person rather than his or her opinions or arguments. Example:

Green Peace's strategies aren't effective because they are all dirty, lazy hippies.

In this example, the author doesn't even name particular strategies Green Peace has suggested, much less evaluate those strategies on their merits. Instead, the author attacks the characters of the individuals in the group.

Ad populum:
This is an emotional appeal that speaks to positive (such as patriotism, religion, democracy) or negative (such as terrorism or fascism) concepts rather than the real issue at hand. Example:

If you were a true American you would support the rights of people to choose whatever vehicle they want.

In this example, the author equates being a "true American," a concept that people want to be associated with, particularly in a time of war, with allowing people to buy any vehicle they want even though there is no inherent connection between the two.

Red Herring:

This is a diversionary tactic that avoids the key issues, often by avoiding opposing arguments rather than addressing them. Example:

The level of mercury in seafood may be unsafe, but what will fishers do to support their families?

In this example, the author switches the discussion away from the safety of the food and talks instead about an economic issue, the livelihood of those catching fish. While one issue may affect the other it does not mean we should ignore possible safety issues because of possible economic consequences to a few individuals.

Straw Person:

This move oversimplifies an opponent's viewpoint and then attacks that hollow argument.

People who don't support the proposed state minimum wage increase hate the poor.

In this example, the author attributes the worst possible motive to an opponent's position. In reality, however, the opposition probably has more complex and sympathetic arguments to support their point. By not addressing those arguments, the author is not treating the opposition with respect or refuting their position.

From: Owl @ Purdue https://owl.english.purdue.edu/owl/resource/659/03/

Glittering Generality:

The use of vague, emotionally appealing virtue words that dispose us to approve something without closely examining the reasons.

Coach said to possible supporters, "We have the greatest team ever and it deserves your support."

Appeal to Questionable

Authority: Supporting a conclusion by citing an authority who lacks special expertise on the issue at hand.

When questioned about the type of physical training he was using for his players, Coach said that this type of physical training was recommended by Oprah Winfrey on her talk show.

Wishful Thinking:

Making the faulty assumption that because we wish X were true or false, then X is indeed true or false.

Coach says that a curfew is not needed since his players should know how to take care of themselves physically.

Explaining by Naming:

Falsely assuming that because you have provided a name for some event or behavior that you have also adequately explained the event or behavior.

Coach claimed that he did not remember what the athletic director had just said because he had a "senior moment."

Searching for Perfect Solutions:

Falsely assuming that because part of a problem would remain after a solution is tried, the solution should not be adopted.

Coach did not try to enforce the curfew because he knew that some players would not honor it.

From: https://illinoisstate.edu/