Logical Fallacies

Informal Fallacy

(Inductive Fallacies and Inductive Arguments) ex: 1)Everyday to date the law of gravity has held. Therefore: 2) The law of gravity will hold tomorrow.

Either/Or

Also called a false dilemma. It occurs when a person says that there are only two choices when there are actually more.

Bandwagon

Occurs when you try to convince people that something is true because a large amount of people believe it is true. .............................................................................. ex: The Bandwagon is a fallacy in which a threat of rejection by one's peers (or peer pressure) is substituted for evidence in an "argument." This line of "reasoning" has the following form: Person P is pressured by his/her peers or threatened with rejection. Therefore person P's claim X is false. This line of "reasoning" is fallacious because peer pressure and threat of rejection do not constitute evidence for rejecting a claim. This is expecially clear in the following example: Joe: "Bill, I know you think that 1+1=2. But we don't accept that sort of thing in our group. " Bill: "I was just joking. Of course I don't believe that.

Formal Fallacy

(Deductive Fallacies and Deductive Arguments) ex: 1) All men are mortal. 2) Socrates is a man. Therefore: 3) Socrates is mortal. ...................................................... It is not possible that both (1 & 2) are true and number 3 is false so this argument is deductively valid.

Fallacy of Composition and Division

A fallacy of division occurs when one reasons logically that something true for the whole must also be true for the parts that make up the whole. ..................................................................................... ex: Logical Form: A is part of B A has property X Therefore, B has property X. Example #1: Each brick in that building weighs less than a pound. Therefore, the building weighs less than a pound.

Straw Man

A weak argument that can easily be refuted. It can be extreme or oversimplified version of the opponent's actual position. .................................................................................... The Straw Man fallacy is committed when a person simply ignores a person's actual position and substitutes a distorted, exaggerated or misrepresented version of that position. This sort of "reasoning" has the following pattern: Person A has position X. Person B presents position Y (which is a distorted version of X). Person B attacks position Y. Therefore X is false/incorrect/flawed. ex: "Senator Jones says that we should not fund the attack submarine program. I disagree entirely. I can't understand why he wants to leave us defenseless like that."

Begging the Claim

Assumes that a statement is self-evident when it actually requires proof. a conclusion based on such assumptions cannot be valid. .................................................................................. Logical Forms: Claim X assumes X is true. Therefore, claim X is true. Example #1: Paranormal activity is real because I have experienced what can only be described as paranormal activity. Explanation: The claim, "paranormal activity is real" is supported by the premise, "I have experienced what can only be described as paranormal activity." The premise presupposes, or assumes, that the claim, "paranormal activity is real" is already true.

Circular Argument

Closely related to begging the question, circular reasoning occurs when someone supports a statement by restating it in different terms.

Red Herring

Distracting with an irrelevant issue. ................................................................................ ex: Mike: It is morally wrong to cheat, why would you do that? Ken: But what is morality? Mike: It's a code of conduct. Ken: But who creates the code?

Hasty Generalization

Jumping to a conclusion. Occurs when someone reaches a conclusion based on too little evidence. .............................................................................. ex: One guy cheats on his wife therefore all guys are cheaters.

Slippery Slope

Occurs when a person argues that one thing will inevitable result from another. Once you permit certain acts, you inevitable permit additional acts that lead to disastrous consequences. ............................................................................. If A happens then B-Z will happen so A=Z. ex: If I make an exception for you I have to make an exception for everyone.

Ad Hominem

Occurs when someone attacks the character or the motives of a person instead of focusing on the issues. ........................................................................... Think of Donald Trump in the 2016 primaries.

Genetic Fallacy

This conclusion is based on an argument that the origins of a person, idea, institute, or theory determine its character, nature, or worth. ....................................................................... ex: A Genetic Fallacy is a line of "reasoning" in which a perceived defect in the origin of a claim or thing is taken to be evidence that discredits the claim or thing itself. It is also a line of reasoning in which the origin of a claim or thing is taken to be evidence for the claim or thing. This sort of "reasoning" has the following form: The origin of a claim or thing is presented. The claim is true(or false) or the thing is supported (or discredited). It is clear that sort of "reasoning" is fallacious. For example: "Bill claims that 1+1=2. However, my parents brought me up to believe that 1+1=254, so Bill must be wrong." It should be noted that there are some cases in which the origin of a claim is relevant to the truth or falsity of the claim. For example, a claim that comes from a reliable expert is likely to be true (provided it is in her area of expertise).

Post Hoc Ergo Propter Hoc

This fallacy asserts that because two events occur closely in time on event must cause the other. .............................................................................. ex: (1) Most people who are read the last rites die shortly afterwards. Therefore: (2) Priests are going around killing people with magic words!

Moral Equivalence

This fallacy compares minor misdeeds with major atrocities. .......................................................................... ex: That parking attendant who gave me a ticket is as bad as Hitler.

What is a logical fallacy?

a logical fallacy is an error in reasoning.

Ad Populum

appeal to popularity. This is an emotional appeal that speaks to positive (patriotism, religion, democracy) or negative (terrorism, fascism) concepts rather than the real issue at hand. ....................................................................................... ex: "I read the other day that most people really like the new gun control laws. I was sort of suspicious of them, but I guess if most people like them, then they must be okay."