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Help with Logical Fallacies

quixotecoyote said:
You have to make the bold section explicitly within the argument. Otherwise it is fallacious AND false rather than merely false.
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Well, it depends. Amongst Christians they might be happy to take it as read that God is as God is said to be, because that's part of their definition of God. So while it wouldn't get full marks in a formal logic exam or anything, it wouldn't be wrong in an important sense either if everyone involved was the kind of person who believed that anyway.
 
I'm only just starting to learn about logic myself. Could you explain the differences between
sound, true and valid?
 
Ok cool, thank you guys.

The unsoundness (is that even a word) or that it is untrue actually proves the point I am making in my argument. I just wanted to make sure that the logical construct was correct.

Does a logical statement require two premises or can it work with one?

McCragge
 
Kevin_Lowe said:
Well, it depends. Amongst Christians they might be happy to take it as read that God is as God is said to be, because that's part of their definition of God. So while it wouldn't get full marks in a formal logic exam or anything, it wouldn't be wrong in an important sense either if everyone involved was the kind of person who believed that anyway.
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Agreed. I was just trying to be specific to prevent misunderstandings.

Splossy:

Valid means that the conclusion follows from the premises.

Sound means that the premises and conclusion are true

The definition of true is an insane ongoing philosophical poo-slinging contest that has been ongoing for the last 2500 years minimum and probably back into pre-history.

Figure it just means correct and your head won't explode. :)
 
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Thx. So can an argument be sound yet invalid? Like: cheese is made of milk, the sky is blue therefore cars are a means of transport.
 
McCragge said:
Ok cool, thank you guys.

The unsoundness (is that even a word) or that it is untrue actually proves the point I am making in my argument. I just wanted to make sure that the logical construct was correct.

Does a logical statement require two premises or can it work with one?

McCragge
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There are many ways to construct a logical statement. I've been keeping it very basic here because that's all I'm capable of.

At minimum you want to express an assumption (major premise), express an instance relating to that assumption (minor premise), and express what happens when you apply the assumption to the instance (conclusion).

If you move things into a different order or mix the parts together it doesn't change the validity. You could break apart your latest example into a bunch of different assumptions and instances, but it wouldn't change the validity.
 
Splossy said:
Thx. So can an argument be sound yet invalid? Like: cheese is made of milk, the sky is blue therefore cars are a means of transport.
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According to my source, no. Both the premises and the conclusion have to be true for the argument to be sound.

You conclusion can still be true, but your argument would still be unsound.

eta:actually, maybe it can. I go to reread.

eta2: Yes, I'm right. The actual way they describe it is that the argument has to be valid and the premises have to be true before the argument can be sound. However, any valid argument with true premises produces a true conclusion, so I got confused.
 
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My logic professor just pounded into our heads that "validity relates to form, and soundness to content." And this is what's being said by Quixote, so I'm not disputing his posts. :D We also memorized "true premises cannot lead to a false conclusion, but false premises can lead to a true conclusion. We call the latter 'lucking out,' and yes, that's a technical term."

She had a great sense of humor, my prof. :p
 
McCragge said:
Does this argument hold water?

P1: If you believe in God you will receive whatever you ask for in prayer
P2: if prayed for nothing will be impossible to you
C1: Amputees will get limbs back if they pray and believe in god

McCragge
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There is nothing in the premises which states that all amputees are "yous" (I'm assuming C1 implies "All").
Neither does the conclusion state that amputees have to pray for limbs to come back.

P2 adds nothing.

As quixotecoyote said, it can be made to follow logically if the audience are happy to fill in those details.
 
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Lonewulf said:
Wait wait wait wait.

Wait.

Just... wait.

Wait.

*mind breaks*

Okay, there we go.

How is saying "someone says something happened, therefore it happened" logical? If I say I turned into superman and beat up Dustin Kusselberg with a giant trout, that doesn't mean the event actually happened.
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It's not.

In fact, it's circular reasoning of the sort all religions depend upon: we know that God created the universe because God says (in the Bible) that God created the universe.

Dun't work logically.

Tokie
 
McCragge said:
Does this argument hold water?

P1: If you believe in God you will receive whatever you ask for in prayer
P2: if prayed for nothing will be impossible to you
C1: Amputees will get limbs back if they pray and believe in god

McCragge
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No. And it's even worse on the assumption and false premise angles.

Let's look at it from the Christian perspective (since that's the one you hope to slam here):

P1: it's secularist misconception that in Christianity, we are taught to use prayer for selfish ends. Just the opposite, in fact: you may pray for God to make you into a better or more "whole" person, but not for things like new or even extra limbs...or to hit the lottery or get to hit that babe in the next office, either. Not how it works in the Christian faith, anyhow.

So you start with a false and predictably bigoted assumption about "prayer" and its conection to God.

P2: not much different from P1, just a restating of a bigoted perspective.

C1: Christians often believe in the power of prayer to heal, but your conclusion is drawn from two false assumptions, so of course it's not going to be logical.

Tokie
 
Validity only requires that the conclusion justifiably be derived from the main premise-nothing more. Validity does not assure that the conclusion reached is true or even the prmise itself is true.

For example:

All Martians are stupid.
Joe is a Martian.
Joe is stupid

Both premise and conclusions are false but the argument is considered valid because the premise justifies the conclusion.

If the conclusion would have been "Joe is not stupid" then the aregument is considered invalid due to the unjustified conclusion.

Whether Joe is or is not a Martian or whether he is or is not stupid has absolutely nothing to do with validity as understood in the use of syllogisms.

If Joe created the universe he is good.
Joe created the universe.
Joe is good.

Valid argument though clearly Joe doid not create the universe and Joe might be a criminal.


Here are other examples of valid arguments:

All Mice are people
All sons are Mice
All sons are people

All people are mean
Some soldiers are not mean
Some soldiers are not people

Some men are not pure
All men are savages
Some savages are not pure

http://www.philosophypages.com/lg/e08b.htm

As you can see validity as the term is used in logic is not dependent on truth of premise or conclusion but simply on the relationship between the twain.
 
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McCragge said:
Hey guys, I am still trying to hone my skills at the art of argument. But of course I am finding that it can be a lot more difficult then it looks. (at least for me) So I thought I would post an example or two and maybe you could help point out the fallacies (if there are any) and why they are fallacies.

+_+_+_+_+_+_+_+


Jack can't hate Jill if Jack doesn't exist.

+_+_+_+_+_+_+_+

Thanks in advance.

McCragge
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This idea is based on the presumption that hatred can not exist outside the mind of a specific hater. Therefore if we consider this hypothetical "Jack" it is a prerequisite of his exhibiting the emotion "hate" that he must first have a mind to hate with. If Jack has no physical existence from which to originate his hatred, then it is in fact safe to assume that Jill will not be hated by him.

This is probably why she pushed him down the hill. The hate was getting to her.
 
Originally Posted by McCragge
Does this argument hold water?

P1: If you believe in God you will receive whatever you ask for in prayer
P2: if prayed for nothing will be impossible to you
C1: Amputees will get limbs back if they pray and believe in god
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The argument is better stated as follows:

God grants all requests made via prayer
An amputee requested to grow a new limb via prayer.
The amputee's request was granted.

Valid argument, but as previously explained, false premise makes it fallacious.
God does not answer all prayers as requested. Sometimes he never answers them at all.
Or if he does respond, it need not be in the manner or at the time requested. He also has the option of not listening to all prayers but only to those qualified. So some persons might very likely be praying to themselves since God might have chosen not to listen.

Of course an atheist would imediately reject the argument as false due to his disbelief atheism.


McCragge
 
McCragge, here's the initial problem (I think): the person who made the statement in your original post is referencing a specific argument (not type of argument, an actual argument that is used by anti-religious). Either he read it and is bringing it to you, or you tried to use it against him, and he wasn't sure what to say in response, but had an idea of where he was going.

The argument is, generally, if the Christian God exists, he must hate amputees because he is all-powerful and thus has the power to grow them new limbs. It is usually put forward as part of the logic statement: amputees exist, therefore God either (a) does not exist, (b) is not all powerful, or (c) is not all good (because he won't cure these people). Of course this ignores other possibilities (maybe all amputees are evil...), but that's the gist of it.

It sounds like your friend wanted to argue: "Atheists often say God hates amputees. if that's true, then God exists because in order to hate, the hater must exist."

This is flawed in a variety of ways. It is based on a false premise. It is a variety of the straw man argument. And, even conceding his point (God exists), it requires an explanation as to why God hates amputees (the first premise).
 
A1 I am always right
A2 If I say I'm always right, it probably means I'm wrong
A3 However, sometimes I am actually right
A4 I'm a pathological liar

:D
 
VillageIdiot said:
This idea is based on the presumption that hatred can not exist outside the mind of a specific hater. Therefore if we consider this hypothetical "Jack" it is a prerequisite of his exhibiting the emotion "hate" that he must first have a mind to hate with. If Jack has no physical existence from which to originate his hatred, then it is in fact safe to assume that Jill will not be hated by him.

This is probably why she pushed him down the hill. The hate was getting to her.
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This presumes that the reporting is accurate to begin with.

In modern American reporting anytime a womyn (Jill, being a pre-womyn)is injured (falling down the hill) and a man(Jack: all men are potential rapists) is anywhere near, it's a given that the man is responsible either directly or indirectly for the injury.

In the original, BOTH Jack and Jill went up the hill while engaged in what the patriarchy suggests in the tale was a cooperative effort to obtain a certain amount of water. We know it's far more likely Jack was either forcing Jill, his chattel, to go up the hill as his beast of burden, or because he was hoping to rape her there. The original data suggest that Jack, being a typical, overweight, clumsy, two-left-feet type American male, then managed to fall down the hill. Now, the original information does not tell us that Jack did anything to cause Jill to "come tumbling after," but we can assume that in his abject cowardice Jack, an American male, remember, must have screamed like a little girl, clutched wildly at Jill (GI Jill, some would call her) and probably because she was at the time navigating loose scree or some such, managed to trip up his physical, intellectual and moral better, Jill, causing her to fall as well.

Tokie
 
Tokenconservative said:
No. And it's even worse on the assumption and false premise angles.
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Actually, since there is a bible verse that states that anyone who prays will have his prayer granted no matter how absurd or extreme the request (I'm sure a more diligent forumite will have the reference handy and post it if required), the argument should read as follows:

P1 - The Bible states that God grants all prayer requests.
P2 - Some people believe that the bible is inerrant.
P3 - When amputees pray for their limbs to spontaneously regenerate, it does not happen.

C1 - The Bible is not inerrant.

Alternatively,

P1 - Some people believe that God will heal any injury through sincere prayer.
P2 - When amputees sincerely pray for spontaneous limb regeneration, it does not happen.

C1 - God will not, in fact, heal all injuries through prayer.

Or my personal favourite,

P1 - When Cthulu awakens, his followers will be eaten first.
P2 - Cthulu will soon rise from his long sleep.

C1 - Therefore, F'taghn!
 
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