Logical Fallacies: A Guide to Identifying and Avoiding Errors in Reasoning, Schemes and Mind Maps of Logic

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Logical Fallacies

What is a logical fallacy?

A logical fallacy is an error in logic that can make a

plausible, but misleading argument.

Inductive fallacies:

Inductive fallacies are the result of the incorrect use of evidence. Ex: “This chalk is white; therefore, all chalk is white.” With inductive fallacies, an arguer leaps to a conclusion based on insufficient evidence

Deductive fallacies:

Deductive fallacies are the result of a failure to follow the logic of a series of statements. Ex: “All birds have beaks. A squid has a beak. Therefore, a squid is a bird.” With deductive fallacies, an arguer makes an incorrect or unsupported link between cause and effect

#1.) HASTY GENERALIZATION:

Prematurely jumping to a presumptuous conclusion.

Prejudices and superstitions are the result of making a hasty generalization.

Ex: “There was a news story about a guy in a fraternity who was a rapist, so now I carry mace if I know I’ll be going anywhere near a frat house.”

How is this an example of the Hasty Generalization logical fallacy?

It’s a prejudiced point of view. The arguer assumes that because one person in a fraternity is a rapist, all people in fraternities are rapist. The arguer is jumping to a presumptuous conclusion about people in fraternities.

#1.) HASTY GENERALIZATION (cont.):

Ex: “Last time I walked past a black cat, I tripped and hurt my arm, so now I avoid black cats altogether.”

How is this an example of the Hasty Generalization logical fallacy?

It is a superstitious belief. The arguer is assuming that the cat caused her to initially injure herself, so now she extends that fear to all cats. She is jumping to a presumptuous conclusion about cats.

#3.) POST HOC or DOUBTFUL CAUSE:

Assuming that because one event follows another, the first event is the cause of the second.

Ex: “The rooster crows at 5:00 AM, and the sun rises at 5:00 AM; therefore the rooster makes the sun rise.”

How is this an example of the Post Hoc logical fallacy?

The arguer assumes that simply because these two events occur sequentially, there is a cause and effect relationship between them.

#3.) POST HOC or DOUBTFUL CAUSE (cont.):

Ex: “A tornado hit my town after a group of Satan worshippers moved in, so God sent the tornado to punish us for allowing them to move here.”

How is this an example of the Post Hoc logical fallacy?

The arguer assumes a connection between the Satan worshippers and the tornado.

#4.) FALSE ANALOGY (cont.):

Drawing an analogy or comparison between two situations that are totally dissimilar.

Ex: “Employees are like nails. Just as nails must be hit in the head in order to make them work, so must employees .”

How is this an example of the False Analogy logical fallacy? The arguer assumes that nails and employees are analogous. She assumes that a method that works for a tool will work for a person.

#5.) AD HOMINEM:

Attacking a person’s character rather than their statements.

Latin for “to the man.”

Ex: “Ernest Hemingway was an alcoholic and a terrible father, so I won’t read his books.”

How is this an example of the Ad Hominem logical fallacy?

The arguer is attacking Ernest Hemingway’s character rather than his intellectual output.

#6.) FALSE DILEMMA:

Poses an “either/or” situation by suggesting that only two options are possible.

Sometimes called the “black/white” fallacy

Ex:

“If you don’t watch football, you’re not a real man.”

How is this an example of the False Dilemma logical fallacy?

This statement poses an “either/or” scenario in which a person either watches football (therefore making them a “real man”) or that person does not watch football (in which case they are not a “real man”).

#6.) FALSE DILEMMA (Cont.):

Ex:

“…here’s my first piece of advice: you must learn to be a problem solver not a problem creator.”

• Bill O’Reilly, Who’s Looking Out For You?

How is this an example of the False Dilemma logical fallacy?

Bill O’Reilly poses a situation in which one is either a “problem solver” or a “problem creator” without evaluating any middle ground in between the two.

#7.) SLIPPERY SLOPE (Cont):

Ex:

“If they legalize marijuana, then they will legalize heroin, then they will legalize suicide, then they will legalize murder.” How is this an example of the Slippery Slope logical fallacy? The arguer jumps to the conclusion that if marijuana is legalized, then other undesirable things will also be legalized.

#8.) BEGGING THE QUESTION:

A circular argument. When an arguer makes a statement that assumes that the very question being argued is already answered.

Ex:

“Women should not be permitted into the men’s club because the club is only for men.”

How is this an example of the Begging the Question logical fallacy?

The arguer does not adequately answer the original question (“why shouldn’t women be permitted into men’s clubs?”). Instead, the arguer treats the question as if it has already been answered.

#9.) STRAW MAN:

Setting up an extreme example of an opposing view to argue against.

Ex:

“Listen, you trust-fund babies and children of privilege, if you’re going to drink a quart of bourbon every day and smoke crack, this book is not for you.”

• Bill O’Reilly, Who’s Looking Out For You?

How is this an example of the Straw Man logical fallacy?

Bill O’Reilly sets up an extreme example of “trust-fund babies” and “corporate weasels.” His example is so extreme that it becomes very easy to argue against.

#10.) TWO WRONGS MAKE A RIGHT:

A rebuttal to an argument which does not refute the allegations, but simply counterattacks.

Ex:

“My stepdad says I’m irresponsible, but I’m not. Besides, he’s a jerk.”

How is this an example of the Two Wrongs Make a Right logical fallacy?

The arguer does not refute the allegations that they are irresponsible; instead, they simply counterattack. The arguer assumes that if the stepdad is wrong, it justifies his actions.