Avoiding Logical Fallacies

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What are Logical Fallacies?

Many professors assign students a "logical fallacies" assignment so that students can understand and avoid fallacies in their argumentative papers. So what are they? Logical fallacies are flaws in reasoning that detract from the overall value of an argument. Politicians are often guilty of using logical fallacies in an attempt to gain public support. Writers, however, cannot resort to such tactics, especially because writing is usually closely evaluated. Good writers avoid using logical fallacies because they detract from the value of an argument rather than add to it. 

Common Logical Fallacies

Hasty Generalization 

Also called overgeneralization. The writer bases the argument on insufficient evidence. The writer draws a larger conclusion than the evidence supports.

Gen-Z tends to be self-centered and materialistic.  My friends Eric and Melanie certainly are.

Non Sequitur (“it doesn’t follow”)

The writer’s conclusion is not necessarily a logical result of the facts.

Tens of thousands of Americans have seen lights in the night sky that they could not identify. The existence of life on other planets is fast becoming certainty.

Begging the Question/ Circular Reasoning

The writer presents as truth what is not yet proven by the argument. (Before an argument on a topic can be made or a solution offered, the reader must be convinced that there is a problem.)

Belief in God is universal. After all, everyone believes in God.

Ad Populum (“to the people”)

 The writer evades the issues by appealing to the reader’s emotional reactions to certain subjects.

If you're patriotic, you'll vote for me.

Either/or

The writer tries to convince readers the issue has only two sides. Most reasonable people understand a middle ground often exists, especially when dealing with complex issues.

Either you’re for protecting our border, or you’re against it.

Bandwagon Appeal

The writer tries to validate a point by suggesting that "everyone else believes in this."

The American people understand that President Jones is wrong on the issue of inflation.

Straw Man

The writer selects the opposition’s weakest or most insignificant point to argue against.

Christians believe in a bearded man up in the sky- that’s ridiculous!

Faulty Analogy

The writer uses an extended comparison as proof of a point.

You know who else liked dogs? Hitler! 

Card Stacking

The writer selects only data that supports the writer's own viewpoint and ignores contradictory data. 

Lose weight fast with our miracle diet pill! 

(Diet pill helps you "lose weight" by making you ill.)

Slippery Slope

The assumption that one thing leads to another (the next step).

First, the government stops us from buying assault rifles.  Then, it limits the number of handguns we can buy.  What will come next?  Will we need a permit to buy a water gun, too?

Post Hoc Ergo Propter Hoc

Assuming that one thing caused another without sufficient evidence.

In the video below, Sheldon's mother assumes he arrived home safe from a trip because she prayed for him.