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I have always wanted to make a compilation of logical fallacies, and here it goes.

What is a fallacy?

A (logical) fallacy is an argument that, while used to back a conclusion or idea, does not actually give any rational support to it. Its logic is faulty. An argument may be logic and false, and ilogic and true. Logic does not deal with truth, which can be circumstantial, but with argument validity, which is strictly either correct or incorrect, and can be proven so in strictly rational grounds. Two examples:

  The moon is made of cheese.

  I wear trousers, therefore tomorrow it will rain.

The first sentence is logical, in the sense that it doesn't contain a contradiction, whereas the second one is not. The second sentence contains a logical fallacy (actually, a non sequitur), even if I wore trousers and the following day would end up raining: the reasoning is defective, because the conclusion (tomorrow raining) doesn't follow the premise (me wearing trousers).

Fallacy equals falsity?

Not at all. I have tried to make a comprehensive list of different kind of logical fallacies, and these foul arguments are always defective, and should never be accepted. However, an argument not being valid (because it is a logical fallacy) does not guarantee its conclusions to be false (assuming that would be another logical fallacy), just renders the reasons given useless. The conclusion might be true, but not for the reasons given.

Fallacies: Manual

Any argument sporting fallacies is bullshit, and you can, and should, have none of it. Just tell the person you are argueing with that her latest sentence was a strawman argument and watch in awe as you actually come up on top! Better yet, watch out for this kind of argumentation, and don't ever use it yourself.

Labeling an argument as fallacious is NOT itself an argument against what the opponent defends (with her foul arguments). We don't thus prove our opponent is wrong, but rather point out that the argument she offers is invalid. Maybe there are other arguments, and she is welcome to use them. But the last one did not add a tiny bit of credibility.

But many fallacies are very similar!

It might seem that I've made up an artificial number of "different" fallacies, when only a few exist. This is actually true, even to a higher degree than the reader might think. When all is said and done, there is only one kind of fallacy: the non sequitur. All fallacies are modifications to this one.

However, I (and all the people making this kind of lists) believe that a comprehensive classification may help the reader recognize fallacies under any of the infinite masks behind of which they hide them.

Sources

A lot of information was taken form the following sources:

List of fallacies

Formal fallacies

Non sequitur

Denying the antecedent

Affirming the consequent

Relevance fallacies

Ad hominem

Recall that the last example is a logical fallacy. The fallacy could be removed by rephrasing to: "Tobacco company representatives may be biased when they say smoking doesn't seriously affect your health, because of their own multi-million-dollar financial interests. Thus, such statements may be wishful thinking, or even outright lies, on their part." Their economical interest is an argument in favor of them being biased, but does not remove (or add) validity to their claims, directly.

Appeal to authority

Argument from ignorance

Ad hoc hypothesis

Appeals to emotion

Appeal to consequences

Appeal to force

Appeal to fear

Appeal to flattery

Appeal to pity

Appeal to ridicule

Appeal to spite

Wishfull thinking

Appeal to tradition

Fallacies of corrupt statistics

Biased sample

Hasty generalization

Fallacy of accident

Appeal to statistics of small numbers

Questionable causality

Post hoc ergo propter hoc

Correlation implies causation

Begging the question

Fallacy of many questions