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Logical Fallacies
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Posted 4/9/08 , edited 4/18/08

magnus102 wrote:

Think of it this way: 1. All men are mortal 2. Socrates is a men 3. Therefore he is mortal. Classic syllogism.


This is just out of curiosity
Is this a categorical syllogism? If so, is Socrates a category? Can this argument be diagrammed with a Venn Diagram?

I tried to diagram this with the Venn Diagram and my teacher marked it off. He said that Socrates is not a Category, therefore I cannot use a Venn Diagram to prove its validity.

Since we cannot use Modus Ponens or Modus Tollens or other valid argument forms to prove the validity of this argument, how do you prove the validity of this argument?



magnus102 wrote:
Appeal to ignorance is saying that because something is not proven false it is true.
Example:
1. You can not prove there is no god
2. Therefore god must exist
In the example above I am making a claim of certainty that is based around the fact my claim has not been disproven. Someone must be saying something is true, because it has never been disproved. If they are not making such a positive claim then there is not a fallacy.


But he did make a definite claim. He asserted that these are not hypotheses. If you look at his post, you will see:



edsamac wrote:
In order for a syllogism to work, and for deductive reasoning to succeed, you need to assure that each object in the syllogism is a factual representation, not a hypothesis or an conceptual claim.

It makes more sense if you put it in the sense of a crime scene of a murder:


There is blood at the scene.

The presence of blood indicates either forced struggle or an assault.

The blood was identified to belong to someone other than the victim.

No other evidence shows participation of any other player in the scene.

Therefore; the blood belongs to the assailant.


This simple example shows how the presence of blood was deduced to belong to the suspect, instead of the victim. All of these are factual statements and are, hence, truthful. If we played with syllogisms, it might look like this:


Blood = struggle/assault

struggle/assault = presence of victim and assailant

Blood =/= victim; other player

Blood = assailant


See? This is the faulty step in the argument:

No other evidence shows participation of any other player in the scene.

Paraphrase: You cannot prove that there was anyone else in the scene.

"You cannot prove that there is no God" ........sound familiar?
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Posted 4/9/08 , edited 4/18/08

magnus102 wrote:
Simple. It sort of like if A=C and C=B than logically must B=A. Since Socrates is a man, and we are saying all men are mortal he must therefore be mortal. No other conclusion is valid given the premise.


So what is the valid argument form called?



He is coming to a conclusion that is not certain, but that is beyond reasonable doubt. Since he is not claiming that his statement is 100% certain since it has not been disproven he has not commited this fallacy.


That is the fallacy, is it not?


Posted 4/9/08 , edited 4/18/08
ummmmmmmm they CAN be true, but most aren't

this guy in my class last year used this:

1)people like to sleep
2)koalas like to sleep

reason:
people are koalas

XDDDDDDDDD
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Posted 4/9/08 , edited 4/18/08

magnus102 wrote:


qweruiop wrote:


magnus102 wrote:
Simple. It sort of like if A=C and C=B than logically must B=A. Since Socrates is a man, and we are saying all men are mortal he must therefore be mortal. No other conclusion is valid given the premise.


So what is the valid argument form called?
Logic


........

My professor would mark the whole question wrong if I answered that........

In the end he told me that, in order to validate this argument, I have to paraphrase the first sentence into a conditional sentence:

All men are mortal.
into
If anything is a man, then it is mortal.

Now we can use Modus Ponens to validate this argument.
Modus Ponens states that if you have a conditional sentence and the antecedent is true, then you can conclude the consequent.

Modus Ponens:

If P then Q
P
----------------
Q

If anything is a man, then it is mortal.
Socrates is a man.
--------------------------------------------------
Therefore, Socrates is mortal.

Since this argument has the form of Modus Ponens now, it is valid. This is because Modus Ponens is a valid argument form.







He is coming to a conclusion that is not certain, but that is beyond reasonable doubt. Since he is not claiming that his statement is 100% certain since it has not been disproven he has not commited this fallacy.


That is the fallacy, is it not?



You do not understand. He did not say that this had to be true because it has not been disproved. He came to a reasonable conclusion that since there is no evidence something occurred then it did not. He is not saying that x has to be true since you can not disprove x. His conclusion is not an argument




Huh? His conclusion is not an argument? What are you trying to say?

In logic, an argument is a set of one or more declarative sentences known as the premises, along with another declarative sentence known as the conclusion.

A conclusion by itself cannot be an argument.....

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Posted 4/10/08 , edited 4/18/08
oh my, this thread reminds me of my Logic class in college... lol ^^
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