[devonin]

It occured to me that in the interests of encouraging intelligent discussion, with appropriate discourse, in a way that really fosters intellectual growth it might be helpful to have a sort of primer for critical thinking around.

In formal logic and argumentation, there are a number of types of faulty reasoning that people are often prone to, called the logical fallacies. These are bits of flawed logic that we all fall pray to at times, but being aware of them and how they work can be very helpful in deciding if your post directly contributes to the discussion at hand.

So with that in mind I'm going to run down all the logical fallacies, and provide an example of each. In most cases I'll be using a pretty absurd and over-the-top (potentially offensive) example simply to highlight how the fallacy works, hopefully since this is a collection of ways to -fail- at argument, it won't be held against me if my post contains inappropriate statements.

Logical Fallacies

Biased Sample - This is where you provide statistical data in support of your point, but those sampled misrepresent the subset of people you are proposing to speak for. Example: Pointing out that 85% of people surveyed opposed gay marriage, when you only surveyed practicing christians. Bear in mind that every sample is biased in some small way, and the biased sample fallacy is only a fallacy if you fail to point out any potential biases when presenting your data.

Hasty Generalization - This is where you conclude something far beyond the scope of existing evidence. Example: That Middle Eastern man was rude to me, all Middle Easterns are rude.

Package Deal Fallacy - This is where you group together concepts that are usually but not always grouped together, functionally misusing an "and" in your description. Example: Concluding that because someone is a liberal and supports welfare, that they must also be pro-choice, and anti-gun.

Fallacy of the excluded Middle or False Dilemma - This is when you present an issue as having only two (or three or whatever) possible conclusions when there are in fact more conclusions possible. Example: Either you are with us, or you are with the terrorists.

Petitio Principii or Begging the question - This is a common fallacy wherein your evidence in support of an argument presupposed that you have already accepted the argument, or requires that you have. Example: The case example of begging the question is arguing the validity of the bible using evidence contained within the bible. In order for the evidence to be acceptable, you have to have already concluded that the bible is valid.

Cum Hoc ergo Propter Hoc or Correlation implies Causation - This fallacy is where you conclude that because two events occur simultaneously, that the two events are necessarily related. Example: When I sneezed, the power went out, therefore my sneeze caused a power outage.

Post Hoc ergo Propter Hoc or False Cause - A similar fallacy to the Cum Hoc fallacy above, in the Post Hoc fallacy you falsely conclude that because two events happened in sequence, the latter was necessarily caused by the former.

Argumentum ad consequentiam or Appeal to consequences - This fallacy is where you conclude that a premise must be right/wrong because the consequences of it being right/wrong are desireable/undesireable. Example: If God didn't exist, life would be meaningless. I desire life to have meaning, therefore God exists.

Argumentum ad Baculum or Appeal to force - This fallacy is where you conclude that a premise is right/wrong because there is a threat of punishment to do otherwise. Example: Believe in God or you will go to hell.

Appeal to probability - A logical fallacy wherein you decide that simply because something is -possible- it is inevitable that it will happen. Example: There are pedophiles on the internet, therefore if you let your child use the internet unsupervised they will encounter a pedophile.

Slippery Slope - A slippery slope fallacy is when you incorrectly (There -are- correct slippery slopes as well) claim that accepting premise A will lead to B->C->D where D is something undesireable, therefore you ought not to accept A. Example: If you legalise marijuana use, more people will start using it, which will make them more likely to use harder drugs.

Ignoratio elenchi or Red Herring - An argument where the conclusion has nothing to do with the premises. Example: I shouldn't get a speeding ticket, there are murderers and rapists out there that the police -should- be chasing. (That there are other criminals has nothing to with the fact that you broke a law and got caught)

Straw Man - The Straw Man fallacy is when you deliberately misrepresent a position in order to make it easier to attack. Examples of this are everywhere: Quoting someone out of context, holding up a weak defender as indicative of all defenders, oversimplifying the other person's argument.

Association Fallacy or Guilt by association - Associating qualities of one thing onto another simply because the two have some kind of link. Example: The Nazis were evil. The Nazis were Germans, therefore Germans are evil.

Argumentum ad Ignorantiam or Appeal to ignorance - The argument that a statement is true simply because it has never been proven false, or that it is false simply because it has never been proven true. NOTE: This does not mean that any time someone points out the lack of proof for something, that they are commiting this fallacy. It is only fallacious to point to lack of evidence if you use that to -CONCLUDE- that the argument is false/true. Pointing out a lack of evidence in general is just good debate.

Appeal to Emotion - An argument where you attempt to convince someone to agree with your argument on emotional grounds rather than on the logical strength of your argument. Example: Any argument that ends with "Think of the children!"

Ad Hominem Attacks- An ad hominem attack is when you direct your argument against the person, rather than their own argument. Example: Why should we listen to you, you're an idiot! (If they're unintelligent, you should be perfectly able to show your disagreement by attacking the point, not the speaker)

Ad Hominem Fallacy- The Ad hominem fallacy is when you use your ad hominem attack to conclude that the person's point is therefore invalid.

Ad populum or Appeal to the Majority - When you present a view such that "everyone knows it is true" to defend your point, rather than actually providing evidence. Example: It's silly for you to claim that Hitler would not have attacked the United States if they hadn't entered World War II. Everyone knows that he planned to conquer the world.

Ad Antiquitatem or Appeal to Tradition - Presenting your view as correct because "It has always been this way" Example: The law has always said that marriage is between a man and a women, there's no reason to change it.

There are a few more, but they are generally minor, or subsets of the larger ones I mentioned above. If I made any glaring omissions, please point them out and I'll add them in, but hopefully even just reading over this will help people draw the distinction between a random conversation or stating of opinion and an actual critical debate or discussion.