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Five Top Logic Lessons


Mad_Gerbil
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Greetings:

 

I'm thinkin' about teaching my kids (10 &13) five logicial fallacies just to whet their appetites for the discipline. I thought there would be nobody better to ask then a bunch of infidels who dabble in logic all of the time.

 

I'm thinking ad homid (*bows to Ramus*) would certainly be at the top of the list, along with red herring - since those seem to be common childhood fallacies. Can you guys put together a good Top 5 list - seeking your opinions here.

 

:woohoo:

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I'll understand if you don't particularly like the source, but practically ALL the argumental fallacies are listed here, latin terms included.

 

 

http://www.biblicalnonsense.com/chapter4.html

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I'll understand if you don't particularly like the source, but practically ALL the argumental fallacies are listed here, latin terms included.

 

 

http://www.biblicalnonsense.com/chapter4.html

 

I've a college level logic text book; however, there are dozens of common logical fallacies.

I guess I'm just trolling for what people think are the most common ones - or perhaps, what 5 they'd teach if they could only teach 5.

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Shifting the burden of proof is a pretty good one. In other words, someone makes a claim then passes the burden of proof onto the disbeliever saying "you can't prove it DIDN'T happen..."

 

Non-sequiturs are also fun. For example: Grass is green, therefore I am the walrus. One simply does not follow the other.

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Guest dualaces123

Appeal to authority is a big one. On a child's level "Well MY mom thinks ..." On a more sophisticated level, "Well,Stanley Fish thinks..." Learning the correct way to use authorities can also be beneficial.

 

I think Ad hominem is a definite must.

 

 

If A, Then B.

B

Therefore, A

(If it is raining, then it is wet. It is wet. Therefore it is raining).

 

Begging the Question

(Abortion is wrong because killing fetuses is murder; murder is wrong; therefore abortion is wrong. This would be begging the question until several points were proved/argued but in itself is not an argument).

 

Strawman Arguments

 

Appeal to Emotion

 

Poisoning the well

 

False Dichotomy / False Dilemma

 

 

Okay - so that is 8, but you can choose which would be most valuable.

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Guest dualaces123

I think they call that argumentum ad populum. In english that would be "Argument to the people" or Argument to the majority.

 

Been too long since I studied informal logical fallacies!

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I'll understand if you don't particularly like the source, but practically ALL the argumental fallacies are listed here, latin terms included.

 

 

http://www.biblicalnonsense.com/chapter4.html

 

 

Good source White! Thanks! I like to touch base with the nonsense of religion to reinforce my own doubts that arise. It must be the fuckin holy spirit trying to influence me! LOL

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In addition to dualaces's example of Affirming the consequent:

 

If A, Then B.

B

Therefore, A

 

There is it's twin brother, Denying the antecedent:

 

If P, Then Q.

not P

Therefore, Q

 

I would say that such fallacies are the result of a person mistakenly treating the conditional statement as a biconditional statement, a statement of the form "P, if and only if Q", and is logically equivalent to "(P implies Q) and (Q implies P)." Notice how it is the conjunction of two different conditionals, one being the converse of the other. To prove the biconditional, both the conditional and its converse must be proven.

 

Of course, there is a major distinction between proving a "P implies Q" statement as opposed to using that statement to prove Q.

 

First of all, "P implies Q" must be proven before you can use it to prove Q (a minor "duh" there). To prove such a statement, the Direct Proof method is to assume P is true, and demonstrate that Q is true. Again, a minor "duh" here, but you can't assume Q is true. That would be considered Begging the Question.

 

Or, if that doesn't work, you can prove the Contrapositive, "not Q implies not P", which is a logically equivalent statement.

 

Once you have proven "P implies Q," all you need to do to show that Q is true is show that P is true.

 

Also, you might get them playing around with Truth Tables.

 

http://en.wikipedia.org/wiki/Truth_Table

 

Have them construct a truth table that shows that "P implies Q" is logically equivalent to "not Q implies not P."

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Oh, and it even took me a little warping of the mind to digest this, but this is the truth table for "P implies Q"

 

P Q P⇒Q
T T  T
T F  F
F T  T
F F  T

 

The cases where P is true are a no brainer... It's the fact that "P implies Q" is vacuously true when P is false.

 

In fact, consider a claim made by a professor at the beginning of the term:

 

"If you pass all tests in this class, you will pass the class."

 

If you consider a student who fails at least one test (which means P is False), s?he can either pass or fail the class and the professor's claim is not contradicted. It simply means that there is no case of a student passing all tests but failing the class (that being P is True but Q is False).

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Guest dualaces123

"There is it's twin brother, Denying the antecedent:"

 

In this case:

"If it is Raining, then it is wet. It is not raining. Therefore it is not wet."

 

You can see how it is virtually the same fallacy as affirming the consequent.

 

 

 

A good exercise is to pick up an LA Times, NY Times, Washington Post, etc. (depending on how educated your chidlren are) and have them look for fallacies. They really are not that hard to find. In fact, you could even have him read ex-christian.net. There are a fair share of fallacies on here (I feel free to say that since I've seen some from Atheists, Agnostics, and Christians).

 

-mike

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Hey MG...you back around here? How did the remodel go?

 

Here's my top list of fallacies that I seem to bounce into and in order of frequency with examples.

 

01. Equivocation

We see this from pundits all the time, usually when Bush is busted on something. "Clinton did it." Colloquially we might say "Two wrongs don't make a right."

 

02. Strawman.

You know this one. I don't need to restate it. Current example I can think of is the unconstitutional spying without FISA oversight that Bush and his cronies are engaged in. Bush says that democrats don't want to catch the terrorists when they insist on oversight.

 

03. Ad hominem

Already stated and I know you know this one already. Recent example was with Al Gore's movie. Instead of refuting the science, lots of pundit assertions were that Gore was going to run again. While that might be the case, hows does that debunk the evidence collected. I did read a more sophisticated species of this argument by a former MIT professor and now a paid pundit of the Competitive Enterprise institute (funded by Exxon I believe) that attacked the meaning of "consensus" itself, but again, not the evidence.

 

Ad hominem can also be reversed too. When a Bush apologist says "You hate Bush" they employee the red-herring. While it may be true I hate Bush, how does that anyway make my point about following the FISA laws any less valid? Does not. It's a change of subject.

 

04. Observational Selection.

I know your familiar with this one. An example I can give (from politics) is how this administration boasts that since 911 we haven't been attacked and this is why "we are safer, but not safe enough." From what evidence can they draw this conclusion? While it is true that the US has not been attacked (paradoxically they admit the biggest disaster on US soil since Pearl Harbor was during their administration) there is no evidence to claim that we are in fact safer. This fallacy relies on the non-sequitar. All that is true is that we haven't been attacked

 

05. Appeal to ignorance

I know your familiar with this one and this one is especially relevant to religious belief, but not necessarily confined to it. I am hard pressed to think of an example outside of religion though.

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Hey MG...you back around here? How did the remodel go?

 

Naw...I just saw that Chef posted and thought I'd say a quick 'Hi'.

The remodel went fine, thanks for asking.

It's nice to be done with that mess.

 

:grin:

 

I'll take a look at these fallacies and pick some of 'em and introduce the kids to the topic.

Thanks for the input.

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