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Logical Fallacies
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Posted 3/31/08
^ Actually, to sum up most of what was said, syllogisms are difficult because they are (more probably than not) absolute statements. 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


The first statement establishes the nature of the crime. In the case of murder, it simply implies there was a struggle or an assault. The second statement works as a definition for the term, and establishes the fact that for there to be a struggle/assault, there has to be a victim and an assailant. The succeeding statements are derived from the other facts of the investigation. This is a form of "ruling out".

A further deduction from these statements includes this:


murder = struggle


The murder can further be classified as a struggle, and not an assault. Working from inferential reasoning, it doesn't make sense that an assault would include the injury of the assailant. Presence of the assailants blood would easily conclude that the victim tried to fight back, hence narrowing down the nature of the murder as a struggle.


I'm just saying these examples to clarify that syllogisms, in themselves, will only work if we're dealing with factual statements. The way you used them were in the form of concepts. Saying that "knowledge is power" may be truthful, but not necessarily factual. The mere fact that the statement can be contended questions it's validity for use in a syllogistic statement.
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Posted 3/31/08

shibole wrote:


makimaki_sataandagi wrote:
I have no idea what its about ....

You are then doomed to be manipulated by propaganda for the rest of your life. You might as well send me all your money now.


................ =.='''
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Posted 3/31/08
I might be too fuzzy about the language but now that this topic is about philosophy, maybe being precise is helpful. In the topic description Shibole wrote: "Fallacious reasoning, and the inability to think critically makes us vulnerable to manipulation by those skilled in the art of rhetoric." and I think there's something conceptually wrong in there. What I have to say is a small thing, but it is worth pointing out just to get things clear.
The part when Shibole says "To think critically" doesn't fit the rest of the sentence as it seems to refer to "Critical thinking" instead of "analytical thinking" that is actually the one benefited from Fallacious reasoning.
The change of terms might be convenient to stick just to one paradigm: analytic philosophy, that looks like is the one relevant here. In Analytic Philosophy logic methods are used to reveal logic consistence, and therefore, the possibility of a certain assertion to be true. In some analytic philosopher's approaches there's still a place for a monadic truth, the one I assume is referred to by Shibole when he writes "keeps us from knowing the truth".
On the other hand there's the critical account, which also produces a way to analyze language but in a very different manner. Critical analysis counts with the philosophical premise that there's not monadic truth, but a relative one, and thus, you analyze discourse in a way that is not necessarily logic, having a complexity that resides not in language’s relation with mathematics but with culture and social matters. “Critical thinking” is more clearly used under this account.

I don’t want to keep you longer with such a small matter. I hope I made my point clear. If you’re interested in Critical Discourse Analysis you might find entertaining some of Van Dijk’s texts on it. You can find lots about this on the net.
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Posted 4/8/08

edsamac wrote:

^ Actually, to sum up most of what was said, syllogisms are difficult because they are (more probably than not) absolute statements. 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.



Hmmmmm........wait a minute! There is a fallacy of reasoning in this argument!

Isn't this what you called "Appeal to Ignorance" on the previous page?

Just because something cannot be proven false, doesn't mean it's true......at least that's what I understood from what you said.




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Posted 4/8/08

qweruiop wrote:

Consider this argument. Is it valid?

Reading is Knowledge. (T)
Knowledge is Power. (T)
Power is Corruption. (T)
Corruption is a Crime. (T)
Crime does not pay. (T)
----------------------------------------------------------
Therfore, reading will make you go broke. (F)

This argument form is the same as yours. It allows an instance of true premises and false conclusion, so is it valid.



This arguement commits the fallacy of the "slippery slope" with structure
R therefore S
S therefore T
T therefore U
R therfore U

It presumes that the first premise lies inevitabley in the conclusion and therefore does not posess any persuasive power.

(I'm sorry if this has already been posted i havn't read the entire thread)
and also i ment no offence to the dude that posted the thing i qouted lol
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Posted 4/8/08

qweruiop wrote:


edsamac wrote:

^ Actually, to sum up most of what was said, syllogisms are difficult because they are (more probably than not) absolute statements. 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.



Hmmmmm........wait a minute! There is a fallacy of reasoning in this argument!

Isn't this what you called "Appeal to Ignorance" on the previous page?

Just because something cannot be proven false, doesn't mean it's true......at least that's what I understood from what you said.


Appeal to ignorance: I don't know the truth value of something, therefore it is true/therefore it is false.

What you are pointing out would be a fallacy if the law dealt only with absolute claims. Recall, however, that we convict or acquit based on whether or not there is reasonable doubt. We can always think that there might have been this, might not have been that, could be more evidence, or could be false evidence present, but then our justice system would necessarily collapse. For the sake of a functional system that protects society, we unintentionally end up imprisoning some innocent people as well because we are not absolutely certain.

We might say that truth-value is often sacrificed for the sake of use-value, but, in this case, it is more important to see that we are confronted with the distinction between absolute truth and reasonably determined truth, an ever-present dilemma in even our day-to-day lives.



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Posted 4/8/08

Ilikecakes wrote:

This arguement commits the fallacy of the "slippery slope" with structure
R therefore S
S therefore T
T therefore U
R therfore U

It presumes that the first premise lies inevitabley in the conclusion and therefore does not posess any persuasive power.

(I'm sorry if this has already been posted i havn't read the entire thread)
and also i ment no offence to the dude that posted the thing i qouted lol


That structure is perfectly valid. The issue here is that the premises themselves are not absolutely true.

Validity and truth are two different concepts in the realm of logic.

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Posted 4/8/08

Regulus133 wrote:


qweruiop wrote:


edsamac wrote:

^ Actually, to sum up most of what was said, syllogisms are difficult because they are (more probably than not) absolute statements. 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.



Hmmmmm........wait a minute! There is a fallacy of reasoning in this argument!

Isn't this what you called "Appeal to Ignorance" on the previous page?

Just because something cannot be proven false, doesn't mean it's true......at least that's what I understood from what you said.


Appeal to ignorance: I don't know the truth value of something, therefore it is true/therefore it is false.

What you are pointing out would be a fallacy if the law dealt only with absolute claims. Recall, however, that we convict or acquit based on whether or not there is reasonable doubt. We can always think that there might have been this, might not have been that, could be more evidence, or could be false evidence present, but then our justice system would necessarily collapse. For the sake of a functional system that protects society, we unintentionally end up imprisoning some innocent people as well because we are not absolutely certain.

We might say that truth-value is often sacrificed for the sake of use-value, but, in this case, it is more important to see that we are confronted with the distinction between absolute truth and reasonably determined truth, an ever-present dilemma in even our day-to-day lives.



This argument does not convict anyone. What I am trying to point out is that it is a fallacy (according to what edsamac said) to say that: since there is no evidence of other players on the scene, the blood belongs to the assailant.

It's like saying: Since we cannot prove that God exists, God doesn't exist.

About the law, however, it does state that one is innocent until proven guilty.
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Posted 4/8/08

qweruiop wrote:

Hmmmmm........wait a minute! There is a fallacy of reasoning in this argument!

Isn't this what you called "Appeal to Ignorance" on the previous page?

Just because something cannot be proven false, doesn't mean it's true......at least that's what I understood from what you said.



For sake of simplicity in an example, we'll say that evidence that discounts someone else from being at the scene can lead to that deduction. I didn't want the example to have to include so many considerations. For what it's worth, focus on the point, and not it's validity as an example. The only reason I put that is so you don't end up jumping to multiple conclusions in a given example.

But if you want to go realistic on this, almost all deductive reasoning isn't 100% accurate. A certain amount of doubt still exists, since it's deductive, but certain evidence can compel an investigator to move towards a certain school of thought regarding his use of logic.

The same exists for practically any branch of science investigating a certain phenomena. In reality, we never work with a 100% accuracy rate, but even something that compels us at a level of 70 or 90% certainty can be enough to make us deduce a logical prognosis.


I hope this makes sense. BTW, that example isn't AI (argumentum ignorantium) because it's not creating an argument, it's just stating a state of events (based on an investigation). In other words, saying "no other people at the scene" would be a statement inferred from gathered evidence, not an appeal against a contrary statement that suggests that someone was there. Because if someone did entertain it, there is still evidence in the scene, though not 100% certain, that highly suggests contrary to the suggestion.

In other words, it's a verifiable fact, not necessarily a challenged argument.

Understand that the point of AI is that you can't use your ignorance as basis for justifying the invalidity of a given argument. AI is actually the "stubborn man's" fallacy, because it results in the failure of one party to recognize obvious facts, while trying to entertain obscure or unreasonable bases.

Using my example, John could commit AI like so.


Patrick: The evidence show's that it's most likely that no one else was at the scene.

John: Someone else was here. I can feel it.

Patrick: How do you say that?

John: Just prove me wrong.


Here, John is obviously overlooking the facts and playing on ignorance to validate his own statement that the original assumption, that no one else was at the scene, is false. This is the actual use of AI ~ you always have to put these logical fallacies into arguments of reasons, because that's the only time they'll pop up. You can't consider my original example to commit AI simply because it was stating compelling facts, not presenting an argument.
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Posted 4/8/08

edsamac wrote:
BTW, that example isn't AI (argumentum ignorantium) because it's not creating an argument, it's just stating a state of events (based on an investigation). In other words, saying "no other people at the scene" would be a statement inferred from gathered evidence, not an appeal against a contrary statement that suggests that someone was there. Because if someone did entertain it, there is still evidence in the scene, though not 100% certain, that highly suggests contrary to the suggestion.

In other words, it's a verifiable fact, not necessarily a challenged argument.

Understand that the point of AI is that you can't use your ignorance as basis for justifying the invalidity of a given argument. AI is actually the "stubborn man's" fallacy, because it results in the failure of one party to recognize obvious facts, while trying to entertain obscure or unreasonable bases.

Using my example, John could commit AI like so.


Patrick: The evidence show's that it's most likely that no one else was at the scene.

John: Someone else was here. I can feel it.

Patrick: How do you say that?

John: Just prove me wrong.


Here, John is obviously overlooking the facts and playing on ignorance to validate his own statement that the original assumption, that no one else was at the scene, is false. This is the actual use of AI ~ you always have to put these logical fallacies into arguments of reasons, because that's the only time they'll pop up. You can't consider my original example to commit AI simply because it was stating compelling facts, not presenting an argument.


Wait.....I'm a little confused. Maybe I got it wrong?

Appeal to Ignorance is when you conclude something to be true, solely under the basis that it can't be proven false. (or vice-versa). Did I get this correct?

So basically: P cannot be proven true, therefore P is false.

Example: You cannot prove God exists, therefore God does not exist.

In the same way your argument says:

There was no evidence (it's not possible to prove) that there were any other people on the scene. So there were no other people on the scene. Therefore the blood must belong to the assailant.

This certainly looks like "Appeal to Ignorance" to me.......

This is definitely a deductively invalid argument, but it seems inductively strong to me.
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Posted 4/8/08

qweruiop wrote:

Wait.....I'm a little confused. Maybe I got it wrong?

Appeal to Ignorance is when you conclude something to be true, solely under the basis that it can't be proven false. (or vice-versa). Did I get this correct?

So basically: P cannot be proven true, therefore P is false.

Example: You cannot prove God exists, therefore God does not exist.

In the same way your argument says:

There was no evidence (it's not possible to prove) that there were any other people on the scene. So there were no other people on the scene. Therefore the blood must belong to the assailant.

This certainly looks like "Appeal to Ignorance" to me.......

This is definitely a deductively invalid argument, but it seems inductively strong to me.


You're taking it too literally. AI is not a concluding statement ~ it's an argumentative statement.

In other words, saying "there is no evidence to show someone at the scene" is a statement of fact in itself. If you're going to use logic, you can deduce that within the bounds of reason, it's safe to conclude that the blood possibly, note... possibly, belongs to the assailant.

I clarified in my last post that I disregarded grounds of speculation for the sake of simplifying the example. What's important is the point that I'm trying to drive, which is that syllogistic statements are only useful for "matter of fact" statements, and not conditional statements.


But to further clear your confusion, AI only presumes that you can't make a statement out of ignorance simply because all forms of argumentative reasoning would be "incomplete" in themselves. In other words, we can never truly prove our statement as absolutely correct, nor can someone contradict it to the latter. AI is not a fallacy that indicates a given statement is wrong ~ rather, it's a fallacy that indicates that contraindicating an argument on grounds of lack of knowledge thereof is flawed in itself.

In the scene of the crime, I already presented enough evidence to assume that there was no one else involved in the incident. This is not contradicting a certain possibility of there being another party, but it is strongly indicative of the former: that there was no other party involved. This is reasoning at it's most basic level. We're not introducing fallacies at this point.

The fallacy comes in when someone wishes to counter the point of evidence the way you're doing it ~ by assuming that it isn't possible to come to such a conclusion based on the speculation of the data (in this case, the evidence) being insufficient.

In other words, I'm going to be frank in saying that you're the one committing AI by assuming that the clause "there is evidence to show no other party at the scene" is false by asking me to defend my claim based on evidence pursued.

If we were to weigh the logic, the factual evidence gives us a safe direction as to what logical path to take, which is the entire point of legal processes. AI is indeed a very tricky fallacy to avoid, but it is simply avoided because it causes a loop of logical cues that will not solve itself. Someone here previously commented on how legal systems cannot function on AI alone, simply because it will lead to the collapse of the entire legal process. Weight of evidence is our sole assumptive power, and it therefore does introduce a certain level of uncertainty.

The problem of accidentally convicting an innocent person or acquitting a guilty man is a possibility that will always arise in legal court. The assumptive powers of human thought can only warn us that AI is dangerous in the court of law simply because it will introduce a loop of arguments that don't really mean anything.


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Posted 4/8/08

qweruiop wrote:

This argument does not convict anyone. What I am trying to point out is that it is a fallacy (according to what edsamac said) to say that: since there is no evidence of other players on the scene, the blood belongs to the assailant.

It's like saying: Since we cannot prove that God exists, God doesn't exist.

About the law, however, it does state that one is innocent until proven guilty.


The argument does commit a fallacy if it is meant to posit absolute claims, but we often work with uncertainty and have to come to decisions based on likelihood. And, while one is innocent until proven guilty, what constitutes "proof" in this case is a lack of reasonable doubt.

I realize the attempt was to create a valid syllogism in a practical context, but logic when applied to the real world very often does have to deal with some degree of uncertainty.

...And I think he already explained the situation better than I did.
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Posted 4/9/08

edsamac wrote:

In other words, I'm going to be frank in saying that you're the one committing AI by assuming that the clause "there is evidence to show no other party at the scene" is false by asking me to defend my claim based on evidence pursued.


I don't think I am commiting Appeal to Ignorance because:

Never did I assume that the above clause is false. Never did I ask you to "prove" your claim. All I said was that, just because there was no evidence doesn't mean that there was no other person on the scene.

Counterexample: Maybe there was evidence (ex: footprints, blood, etc), but the assailant cleaned it up before the police inspectors got there.

We are learning about the different kinds of fallacies in my logic class. This is what my Professor said:

Appeal to Ignorance: P cannot be proven true, therfore P is false. -OR- P cannot be proven false, therfore P is true.

He gave us the following example and asked us if this is Appeal to Ignorance:

There is no evidence to prove that Jimmy commited the crime.
--------------------------------------------------------------------------------------------
Therefore Jimmy is innocent.



The answer, in this case, is no. This is because there is an implicit premise in this argument: One is innocent until proven guilty.

But in your case, there are no implicit premises in the argument.

There is no evidence to prove that there was another person on the crime scene.
----------------------------------------------------------------------------------------------------------------------
Therefore, the only people on the crime scene were the victim and the assailant.



I understand that this is an inductively strong argument, but it's not valid.

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Posted 4/9/08
^ Read what Regulus said above me. We're not questioning validity, we're moving towards rational claim. Again, for the sake of simplicity, discount this peculiarity and understand that I was simply trying to make an example based on syllogistic thought. You can argue as much as you want on the validity of claim, but that's unimportant as far as the point is concerned.

Also, my argument wasn't saying "for certain", it was a statement in the sense of "beyond reasonable doubt". You can't talk of absolute statements in the given example ~ it simply won't make any sense.
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Posted 4/9/08

Regulus133 wrote:


Ilikecakes wrote:

This arguement commits the fallacy of the "slippery slope" with structure
R therefore S
S therefore T
T therefore U
R therfore U

It presumes that the first premise lies inevitabley in the conclusion and therefore does not posess any persuasive power.

(I'm sorry if this has already been posted i havn't read the entire thread)
and also i ment no offence to the dude that posted the thing i qouted lol


That structure is perfectly valid. The issue here is that the premises themselves are not absolutely true.

Validity and truth are two different concepts in the realm of logic.



its an informal fallacy, it doesnt apply to its validity but it is an error in reasoning.
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