What's your favorite logical fallacy?

[Renata]

This is inspired by the recent troll thread that was full of complex questions, by the complex question thrown at Greadius in the 'jealous of America' thread yesterday, and by Mojotronica's typical thread-generating posts.

Here's a link to a rather exhausive list of logical fallacies.

the list (warning - frames)

So what's your favorite, and why? Mine is all variants of the red herring, for sentimental reasons - my sister is a master of the technique, making argument with her a frustrating exercise.

Have you ever taken a class in logic in high school or college? Was it required or optional, and did you find it worthwhile?

How important is it to you that people you debate with use good logic? What about politicians? Talk show hosts? Is use of good logic even necessary if you don't get caught?

Do you enjoy seeking out the flaws in others' arguments? (I do.) Do you call them on it? Do you yell back at the TV or the radio, like I do, saying things like 'you twit, that's the most circular argument I've ever heard!'? Are you willing to criticize your own side of a debate on charges of flawed logic, or do you let it go when you agree with the basic premise?

Any particularly enjoyable examples of truly atrocious logic you've come across lately?

Renata

 

[MrPresident]

The most annoying thing for me is when my brother questions every statement of fact I make by the 'world was flat' approach. I say fact X, he says 500 years ago everyone thought the world was flat therefore we can't be sure about anything ever, so fact X could be wrong. I say, of course, fact X could be wrong but it's not. So we start having an argument about whether fact X is a fact or not, even though it clearly is, rather than the original argument which I was almost certainly going to win. My brother is a master of this technique and has even had me questioning whether 1+1 = 2.

 

[Yago]

Yes, I had some rhetoric at school.

What I've learned was, that logic is not the most important thing. Definition is.

How important is it to you that people you debate with use good logic? What about politicians? Talk show hosts? Is use of good logic even necessary if you don't get caught?

Therefore, logic has no meaning, when it's concluded from something which is defined differently.

Logic leads nowhere, or unbelievable slowly, when A and B argue about something. And if there are two definitions, which can't be put logically together, shism is the only way out.

A's defintion about the world: The world is the center of the Universe.

B's defintion about the world: Planet Earth is just a planet.

B says:"The earth turns around the sun"
A says:"What a giantic bull****. Try some logic. The world is the center of the universe. How can the center turn around anything ?"

Discussion over.

Logic leads nowhere, when people do not agree about definiton of things.

In the giantic realm of the internet, you have to find people who share most of your defintion of things. Logic leads nowhere alone.

My favourite syllogism:

A locomotive is something which makes a whistling sound.

Birds whistle

Birds are locomotives.

ou twit, that's the most circular argument I've ever heard

Once in another forum. I only mentioned, that it's a circular argumentation. Then I was flamed.

 

[CruddyLeper]

Something my first Physics teacher told me that has stuck;-

"If you can't convince, confuse".

 

[napoleon526]

Here's one:

God is love.

Love is blind.

Ray Charles is blind.

Therefore,

Ray Charles is God.

 

[FredLC]

I have been using fallacy lists for a long time now, and I always like to expose the lack of logic and than show the list to back me up.

I like many of them, but my very favourite has to be the appeal to ignorance. I mean, trying to make a point by saying that you know nothing about it is as irrational as it gets.

Regards .

 

[puglover]

Yes! I wanted somebody to make a thread like this!

I like the Snob Appeal.

"You are better than normal people and deserve the best. Buy my product!"

 

[Renata]

Man I'm really tired of this lousy server at work eating my posts. It is truly evil of them not to provide a reliable server for me to waste time.



Anyway, I wanted to point out that Yago's syllogism is a bad one, so can't be used to support any argument that logic in general is useless. (I can't remember the name of the formal fallacy it typifies, but mathematically it can be understood by saying that the first two statements indicate that the sets of 'locomotives' and 'birds' overlap, but not that 'birds' is a subset of 'locomotives'.)

But yes, i do agree that definitional problems can be every bit as frustrating to listen to as logical problems -- just see my post about the radio talk show host in the 'radio' thread.

Renata

 

[Pangur Bán]

I've done a course in logic, it's quite fun, and it ends up that almost everything someone says can be a fallacy. Virtually every scientific statement regarding causation falls victim to "post hoc, ergo propter hoc" fallacy.

 

[Renata]

@ calgacus: Well, no, not if there's actual evidence to back up the correlation. For example, I have a culture of some bacteria. I add soap to their culture medium, and the bacteria all die. I hypothesize that the soap caused the deaths. To prove it, I get two more culture dishes with the bacteria, add the soap to one of the dishes but not the other, and observe that the bacteria in that dish, but not in the other, die. Ergo, adding the soap caused them to die. No logical fallacy there. I suppose the logical fallacy would be if I had considered it proven before actually doing the experiment.

@ puglover: ROFL. I love that one, too.

Renata

 

[Perfection]

Actually earth is the center of the universe

 

[onejayhawk]

I've hadd three courses in Logic/Boolean Algebra. One was the basic Philosphy department course in logic. It was largely a history course. The next was the upper level Philosophy course in logic and rhetoric. There was both textual argumentation and the introduction to symbolic logic, aka Boolean Algebra. Finally I took teh upper division Math course in Foundations Theory, which was more than half Boolean.

My favorite fallacy is the ommitted center. It when someone lays out the ground work for an argument and then jumps straight to the conclusion. The slippery little details of the argument arent glossed over, they are completely missing. The standard rebuttal is that it has already been covered, followed again be a recitation of the facts. My standard reply is something along the lines of "Is that Bad?" followeed by "Why is it bad?"

J

 

[Mojotronica]

Favorite? I don't know -- a circular argument or a slippery slope argument are the ones that I seem to confront the most often. I think people aree basically illogical, and tend to try to make reality fit their perception rather than their perception fit their reality.

I've taken a logic course but I rarely whip out the list of fallacies when I argue. Usually I like to compare the circular argument against another (more obviously false) circular argument and hope that it is convincing, because I worry that dropping the name will poison my opponent against me. No one likes a know-it-all.

Just ask Al Gore.

 

[Pangur Bán]

Originally posted by Renata
@ calgacus: Well, no, not if there's actual evidence to back up the correlation. For example, I have a culture of some bacteria. I add soap to their culture medium, and the bacteria all die. I hypothesize that the soap caused the deaths. To prove it, I get two more culture dishes with the bacteria, add the soap to one of the dishes but not the other, and observe that the bacteria in that dish, but not in the other, die. Ergo, adding the soap caused them to die. No logical fallacy there. I suppose the logical fallacy would be if I had considered it proven before actually doing the experiment.

It still falls victim to the fallacy. You're still presuming that the soap caused the death of the bacteria because the latter followed the former. Generally speaking, that is the problem of induction raised by Hume.

 

[YNCS]

No cat has two tails. A cat has one more tail than no cat (no cat, no tail). Therefore a cat has three tails.

A pen is a writing implement. Pigs live in a pen. Therefore pigs live in a writing implement.

Both of these fallacies operate on the fact that a word can have more than one meaning.

 

[col]

This is a false statement.

Recursion. See recursion - favourite dictionary definition.
Self referential statements are fun. Godel Escher and Bach was such a good book and for the first time I could understand Godel's theorem.

 

[muppet]

My favorite is: post hoc ergo propter hoc.
Because it is all the latin I know.

My degree required one of either Philosophy 101 (Critical Thinking) or History 120 as one of the components of the "breadth requirement" for graduation.

Individuals over the age of 19 should not be permitted to express an opinion until they have attained at least a B+ grade in at least one college level philosophy course.

 

[col]

post hoc ergo propter hoc.

One of my favourite lines in argument is that someone is arguing 'a posteriori' ie they are talking out of their backside.

 

[polymath]

I like the 'no true scotsman' fallacy. i.e.

James: "No true Scotsman would beat his wife"
Dirk: "But McTavish beats his wife"
James: "Then McTavish is not a true scotsman"

 

[col]

I hate the 'Scientists dont know everything' argument.

Me: All the evidence in Physics accumulated over the last hundred years says we cant go faster than light in a vacuum.

Them: Scientists dont know everything so I say we can.

Me : Grrrrrrrrrrrr