All About Logical Fallacies
I have a very low tolerance of logical fallacies because I embrace logic and truth.
If you use any of the logical fallacies below, you are embracing deception and lies. Pay attention to this and rid yourself of all logical fallacies.
Argumentum ad hominem. This logical fallacy connects the argument to the man. You attack the man, prove he is a worthless scumbag, a deceptive clown, and then the argument is proven false.
The problem with this is that it doesn’t work. If it did work, all I have to do is get a worthless scumbag to speak the truth, and thus invalidate it.
Illogical Ian: You’re wrong because you’re a stupid, racist, religious, rich, capitalist pig!
Logical Leo: So, you’re saying that whatever I say is wrong because I’m a stupid, racist, rich, capitalist pig?
Illogical Ian: Of course, you idiot!
Logical Leo: So whatever I say is a lie and completely false?
Illogical Ian: Of course, you racist pig!
Logical Leo: Very well, then I wholeheartedly declare that you, Illogical Ian, are a very nice person, who is logical, trustworthy, and someone all men should worship and emulate.
Illogical Ian: Thanks, but no thanks, you retarded imbecile.
Logical Leo: I also declare, the earth revolves around the sun, scientific investigation is a good way to investigate claims about nature, and that I owe you twenty dollars.
Illogical Ian: I don’t get it, why are you talking so kindly about me and using logic all of a sudden?
Logical Leo: Didn’t you just declare that everything I said was illogical because of who I am?
Illogical Ian: Wait a minute… I see what you did there…
Argumentum ad populum: This common logical fallacy relies on the fact that “everybody” believes it or accepts it as true, therefore it is true. It can also be used to replace specific authorities with a more collective “all scientists”, “all politicians”, “all reasonable people” claim.
Illogical Ian: I know its true, because everyone says its true!
Logical Leo: I don’t think it’s true. So since everyone doesn’t say it’s true, it must not be true, then?
Illogical Ian: Well, most reasonable people say its true!
Logical Leo: It wasn’t too long ago that most reasonable people though that slavery wasn’t a terrible idea.
Illogical Ian: That’s a different thing man…
Logical Leo: And not too long ago, the vast majority of the American public supported the invasion of Iraq.
Illogical Ian: Hold on…
Logical Leo: I can give you plenty of examples where public opinion, or the opinion of a large group of any people, turned out to be wrong. In fact, I can only say with certainty that no one knows everything, or really, anything. At some point, some part of their understanding will be proven wrong. Hopefully, at that point, they will embrace the new understanding and logic. Either that, or leave themselves behind on the dustbin of history.
Affirming the consequent. This is a logical fallacy that everyone seems to make regarding scientific theories. It works like this.
“If P, then Q.” That’s the theory.
“Q.” That means, the predicted results are observed.
“Therefore, P.” This is the fallacy. Just because a theory predicts a result and that result is observed, doesn’t mean the theory is true. There are, after all, a gazillion other theories that could explain the same result, including the simple theory, “God did it.”
If you want to go from “Q” to “P”, then you have to start with “If not P, then not Q.” In other words, prove that the only explanation for Q would be P, since if P is not true, then Q cannot happen.
This is an extraordinarily impossible thing to prove.
Illogical Ian: If it’s raining, then the ground is wet.
Logical Leo: Sounds right.
Illogical Ian: The ground is wet.
Logical Leo: Yes, but I see where you are going and…
Illogical Ian: Well, it must be raining, then!
Logical Leo: Ian, have you heard of affirming the…
Illogical Ian: Grab your umbrella, dude! Hey, why aren’t there any clouds in the sky right now? Who turned the sprinklers on?
Denying the antecedent. This is another fallacy that is just as bad as “affirming the consequent”. It looks like this:
“If P then Q.”
“Therefore, not Q.”
In plain English, “If it’s raining, the ground will be wet.” “It’s not raining.” ‘Therefore, the ground is not wet.”
Logical Leo: Ian, right now might not be the best time for a picnic on the grass.
Illogical Ian: Why not? It’s not raining, so the ground is dry!
Logical Leo: I regret to inform you that…
Illogical Ian: Sandwich?
Logical Leo: … yeah. Enjoy your picnic in the sprinklers, bud.
Changing definitions. This one is harder to catch, because it relies on a subtle trick of language. See, each word can mean more than one thing. And if you reuse the same word, it looks like you are using the same meaning. But this is often not the case.
When logically reasoning, you really have to treat words as symbols. Try to identify what each symbol represents, and be very consistent. If it’s apparent that the speaker is switching definitions, then point that out.
False dilemma. In this logical fallacy, only a few options are presented as possibilities, when in fact there are more.
It’s ok to say “Either X is A or not A.” It is not ok to say, “Either X is A or B” unless you can prove that both A infers not B and B infers not A.
Confusion, or the Chewbacca Defense. This logical fallacy attempts to win the argument by confusing the audience. Unneeded facts and unnecessary correlations are drawn. This is a favorite of conspiracy theorists, since they bring in a ton of information and try to draw a logical conclusion by sheer volume.
To defeat this fallacy, point out what the attacker is doing and get back to the core of the argument. Often, restating the problem in simpler terms, identifying the real points of interest and conflict, will disarm the opponent.
See http://www.virtuescience.com/logicalfallacies.html for more logical fallacies.