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Logical fallacies

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Here's my list:

Since there seems to be alot of the following going on here (and I'm probably guilty of it, too), I thought I'd lay out the classic mistakes people make in putting forth a believable argument. This comes from the classic Greek model of logical arguments.

Uses threats or prediction of gloom to win arguments

The Appeal to Force is committed when the arguer resorts to force or the threat of force in order to try and push the acceptance of a conclusion. It is often used by politicians, and can be summarized as "might makes right". The force threatened need not be a direct threat from the arguer.

For example:

"... Thus there is ample proof of the truth of the Bible. All those who refuse to accept that truth will burn in Hell."

Personal Attacks

The Abusive variety of Arguments occurs when, instead of trying to disprove the truth of an assertion, the arguer attacks the person or people making the assertion. This is invalid because the truth of an assertion does not depend upon the goodness of those asserting it.

For example:

"Atheism is an evil philosophy. It is practised by Communists and murderers."

Saying something is true because it can't be proved not true.

This fallacy occurs whenever it is argued that something must be true simply because it has not been proved false. Or, equivalently, when it is argued that something must be false because it has not been proved true. (Note that this is not the same as assuming that something is false until it has been proved true, a basic scientific principle.)


"Of course telepathy and other psychic phenomena do not exist. Nobody has shown any proof that they are real."

Appealing to the People

Appealing to the People. To commit this fallacy is to attempt to win acceptance of an assertion by appealing to a large group of people. This form of fallacy is often characterized by emotive language. For example:

"The Bible must be true. Millions of people know that it is. Are you trying to tell them that they are all mistaken fools?"

The more who agree with me, the more I must be correct

This fallacy is closely related to the Appeal of People. It consists of asserting that the more people who support or believe a proposition, the more likely it is that that proposition is correct.

Using Endorsements

The Appeal to Authority uses the admiration of the famous to try and win support for an assertion. For example:

"Isaac Newton was a genius and he believed in God."

The fallacy of accident

The Fallacy of Accident is committed when a general rule is applied to a particular case whose "accidental" circumstances mean that the rule is inapplicable. It is the error made when one goes from the general to the specific. For example:

"Christians generally dislike atheists. You are a Christian, so you must dislike atheists."

Converse accident / Hasty generalization

This fallacy is the reverse of the Fallacy of Accident. It occurs when one forms a general rule by examining only a few specific cases which are not representative of all possible cases. For example:

"Jim Bakker was an insincere Christian. Therefore all Christians are insincere."

False Cause fallacies.

The fallacy of False Cause occurs when one identifies something as the cause of an event but it has not actually been shown to be the cause. For example:

"I took an aspirin and prayed to God, and my headache disappeared. So God cured me of the headache."

Circular Argument

This fallacy occurs when one assumes as a premise the conclusion which one wishes to reach. Often, the proposition will be rephrased so that the fallacy appears to be a valid argument. For example:

"Homosexuals must not be allowed to hold government office. Hence any government official who is revealed to be a homosexual will lose his job. Therefore homosexuals will do anything to hide their secret, and will be open to blackmail. Therefore homosexuals cannot be allowed to hold government office."

Note that the argument is entirely circular; the premise is the same as the conclusion. An argument like the above has actually been cited as the reason for the British Secret Services' official ban on homosexual employees.

Complex question / Fallacy of interrogation / Fallacy of presupposition

This is the interrogative form of Begging the Question. One example is the classic loaded question:

"Have you stopped beating your wife?"

Irrelevant Conclusion

The fallacy of Irrelevant Conclusion consists of claiming that an argument supports a particular conclusion when it is actually logically nothing to do with that conclusion.

For example, a Christian may begin by saying that he will argue that the teachings of Christianity are undoubtably true. If he then argues at length that Christianity is of great help to many people, no matter how well he argues he will not have shown that Christian teachings are true.

Sadly, such fallacious arguments are often successful because they arouse emotions which cause others to view the supposed conclusion in a more favourable light.

Fallacies of composition

One Fallacy of Composition is to conclude that a property shared by the parts of something must apply to the whole. For example:

"The bicycle is made entirely of low mass components, and is therefore very lightweight."

The other Fallacy of Composition is to conclude that a property of a number of individual items is shared by a collection of those items. For example:

"A car uses less petrol and causes less pollution than a bus. Therefore cars are less environmentally damaging than buses."

The slippery slope argument

This argument states that should one event occur, so will other harmful events. There is no proof made that the harmful events are caused by the first event.

For example:

"If we legalize marijuana, then we would have to legalize crack and heroin and we'll have a nation full of drug-addicts on welfare. Therefore we cannot legalize marijuana."

It's always been that way

This is the fallacy of asserting that something is right or good simply because it is old, or because "that's the way it's always been."

"You Too" fallacy.

It occurs when an action is argued to be acceptable because the other party has performed it. For instance:

"You're just being randomly abusive."

"So? You've been abusive too."

This is a form of personal attack

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