What is the difference between a fallacious argument and an invalid arguement?

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Deckard
 
Reply Sun 21 Feb, 2010 02:25 am
If an argument is invalid, then it is possible for the conclusion to be false even if all the premises are true.

I have a more difficult time finding a concise definition of a fallacious argument.

Does this work?
A fallacious argument is an argument based on false or invalid inference.

But this suggests that all invalid arguments are also fallacious arguments which in other threads I have been told that this is not the case.
 
Krumple
 
Reply Sun 21 Feb, 2010 02:43 am
@Deckard,
Deckard;130587 wrote:
If an argument is invalid, then it is possible for the conclusion to be false even if all the premises are true.


Yes.

p1. Birds have wings.
p2. Things that have wings can fly.
c1. All birds fly.

The conclusion is false, because not all birds actually can fly.

Deckard;130587 wrote:

I have a more difficult time finding a concise definition of a fallacious argument.


Study the argument closely, study the conclusion closely. Often times you have to make sub arguments for each premise to determine how they relate to the original conclusion.

Deckard;130587 wrote:

Does this work?
A fallacious argument is an argument based on false or invalid inference.

But this suggests that all invalid arguments are also fallacious arguments which in other threads I have been told that this is not the case.


It could be a case made for invalidating an argument but it is not a universal cause for invalidating arguments.
 
Deckard
 
Reply Sun 21 Feb, 2010 02:47 am
@Krumple,
Krumple;130592 wrote:


It could be a case made for invalidating an argument but it is not a universal cause for invalidating arguments.


I don't think that the presence of fallacy invalidates an argument. An ad homenum attack for example:

Al Gore tells only lies
Al Gore says that global climate change is a real problem
Therefore global climate change is a lie

If the premises were true then the conclusion would have to be true.
Yet to say that Al Gore tells only lies is an ad homenum attack so this is a fallacious argument.

I can see that not all fallacious arguments are invalid arguments.

But are all invalid arguments fallacious arguments?
That's the part I'm stuck on. By the definition I provided for fallacious arguments it would seem so but I think that definition may not be technical enough for our purposes.
 
Krumple
 
Reply Sun 21 Feb, 2010 02:58 am
@Deckard,
Deckard;130594 wrote:
I can see that not all fallacious arguments are invalid arguments.
But are all invalid arguments fallacious arguments?


No. Because the conclusion could still be true absent the premises thus it would not be fallacious. This usually only happens during long discourses of validating conclusions. Where a first conclusion (assumed true) is used as a premise to try and make the following conclusions true (assumed false). So in other words it doesn't invalidate the whole argument if one conclusion is false.
 
Deckard
 
Reply Sun 21 Feb, 2010 03:07 am
@Krumple,
Krumple;130599 wrote:
No. Because the conclusion could still be true absent the premises thus it would not be fallacious. This usually only happens during long discourses of validating conclusions. Where a first conclusion (assumed true) is used as a premise to try and make the following conclusions true (assumed false). So in other words it doesn't invalidate the whole argument if one conclusion is false.


So fallaciousness is to the falseness of a premise
as invalidity is to ?
 
Krumple
 
Reply Sun 21 Feb, 2010 05:12 am
@Deckard,
Deckard;130604 wrote:
So fallaciousness is to the falseness of a premise
as invalidity is to ?


Typically a logical fallacy is one where at least one of the premises and the conclusion are both determined to be false. The resultant conclusion doesn't necessarily need to be false for it to be considered a fallacy.

p1. Bricks are used to make buildings.
p2. Bricks make things tall.
c1. All Buildings are tall.

p4. Buildings are tall.
p5. Bricks make things tall.
c2. All buildings use bricks.

c2 is false, however c1 is true. So is it a logical fallacy? Yep, even though there are some true statements.

edit: Actually c1 is not always true if you consider buildings underground but I don't think they actually call them buildings.
 
kennethamy
 
Reply Sun 21 Feb, 2010 07:42 am
@Deckard,
Deckard;130587 wrote:
If an argument is invalid, then it is possible for the conclusion to be false even if all the premises are true.

I have a more difficult time finding a concise definition of a fallacious argument.

Does this work?
A fallacious argument is an argument based on false or invalid inference.

But this suggests that all invalid arguments are also fallacious arguments which in other threads I have been told that this is not the case.


A fallacious argument is an argument whose conclusion fails to follow from it premises. All invalid arguments are fallacious arguments. I can't imagine why anyond would deny that. Your definition won't do since there are not such things a false inferences. Also, it is not clear what the phrase "based on" means.

---------- Post added 02-21-2010 at 08:49 AM ----------

Krumple;130672 wrote:
Typically a logical fallacy is one where at least one of the premises and the conclusion are both determined to be false. The resultant conclusion doesn't necessarily need to be false for it to be considered a fallacy.

p1. Bricks are used to make buildings.
p2. Bricks make things tall.
c1. All Buildings are tall.

p4. Buildings are tall.
p5. Bricks make things tall.
c2. All buildings use bricks.

c2 is false, however c1 is true. So is it a logical fallacy? Yep, even though there are some true statements.

edit: Actually c1 is not always true if you consider buildings underground but I don't think they actually call them buildings.


A fallacious argument may have premises and conclusion all of which are true.

1. All dog are mammals
2. All German citizens are European citizens

3. All planets move around the Sun in elliptical orbits,

The argument is fallacious because the conclusion fails to follow from the premises. As you can tell by inspection.
 
Krumple
 
Reply Sun 21 Feb, 2010 07:58 am
@kennethamy,
kennethamy;130690 wrote:
A fallacious argument may have premises and conclusion all of which are true.

1. All dog are mammals
2. All German citizens are European citizens

3. All planets move around the Sun in elliptical orbits,

The argument is fallacious because the conclusion fails to follow from the premises. As you can tell by inspection.


But no one realistically argues a premise and concludes something different from that premise. It would be like protesting your innocents of a crime and then say well I am however guilty of this other thing, so I guess you should consider me guilty for the first thing.

I didn't kill the neighbors dog.
I did kill a fly once.
c. I guess I am guilty for killing the neighbors dog.

No one ever argues like that. In fact what you propose is even worse. It would be that the conclusion has absolutely nothing to do with the premise at all.

I didn't kill the neighbors dog.
I did kill a fly once.
c. I don't have to work tomorrow.
 
kennethamy
 
Reply Sun 21 Feb, 2010 08:07 am
@Krumple,
Krumple;130693 wrote:
But no one realistically argues a premise and concludes something different from that premise. It would be like protesting your innocents of a crime and then say well I am however guilty of this other thing, so I guess you should consider me guilty for the first thing.

I didn't kill the neighbors dog.
I did kill a fly once.
I guess I am guilty for killing the neighbors dog.

No one ever argues like that.


The point is that the premises may or may not be connected by subject matter. What is crucial is whether the conclusion follows from the premises.

Here is a more conventional argument which is also fallacious:

All Germans are Europeans.
All Berliners are Europeans

Therefore, all Berliners are German.

Premises and conclusion all true, argument is fallacious.

But logically speaking, there is no difference between the two arguments,
 
Krumple
 
Reply Sun 21 Feb, 2010 08:13 am
@kennethamy,
kennethamy;130696 wrote:
The point is that the premises may or may not be connected by subject matter. What is crucial is whether the conclusion follows from the premises.

Here is a more conventional argument which is also fallacious:

All Germans are Europeans.
All Berliners are Europeans

Therefore, all Berliners are German.

Premises and conclusion all true, argument is fallacious.

But logically speaking, there is no difference between the two arguments,


My only problem with it is that your conclusion is false.
 
kennethamy
 
Reply Sun 21 Feb, 2010 08:18 am
@Krumple,
Krumple;130697 wrote:
My only problem with it is that your conclusion is false.


It is? How come? All Berliners who are citizens of Berlin are Germans. So "Berliners"=Citizens of Berlin.
 
Krumple
 
Reply Sun 21 Feb, 2010 08:22 am
@kennethamy,
kennethamy;130700 wrote:
It is? How come? All Berliners who are citizens of Berlin are Germans. So "Berliners"=Citizens of Berlin.


Yeah you can become a citizen OF Berlin but not be German.
 
jgweed
 
Reply Sun 21 Feb, 2010 08:38 am
@Deckard,
How do we determine that an argument is "fallacious" (using for the moment a common sense definition of the word to mean incorrect or "wrong")?

There seem to be several criteria for rejecting an argument.

First, The assertions in the premises are either doubtful (without sufficient warrants for accepting them) or wrong (contrary to matters of fact---this does not mean contrary to what I want to believe---and might also include the aspect of credibility).
Second, words in the premises (and/or conclusion) are used in different senses (e.g. the word "bias").
Third, the argument employs informal fallacies. While this might not necessarily make the conclusion wrong, it does put it into question by not providing a sound argument.
Fourth, the formal structure of the argument from premises to conclusion fails to follow logical rules (this can be similar to step 3), or if premises do follow these rules, the logical conclusion may nevertheless be indeterminate.

From the list that of course could be expanded, it seems clear that we accept or reject arguments to a conclusion using more than (strictly speaking) logical tests.
 
xris
 
Reply Sun 21 Feb, 2010 09:37 am
@jgweed,
Surely debates can be allot more subtle than simply correct or incorrect. What if certain knowledge is questionable and you use it, is it fallacious or invalid?
 
Krumple
 
Reply Sun 21 Feb, 2010 09:39 am
@xris,
xris;130725 wrote:
Surely debates can be allot more subtle than simply correct or incorrect. What if certain knowledge is questionable and you use it, is it fallacious or invalid?


Well now you are talking about ethics and ethics do not care about truths. Truths are not dependent upon ethics. If they are then all truths are subjective which they are not.
 
xris
 
Reply Sun 21 Feb, 2010 09:53 am
@Krumple,
Krumple;130726 wrote:
Well now you are talking about ethics and ethics do not care about truths. Truths are not dependent upon ethics. If they are then all truths are subjective which they are not.
I was thinking more than an ethical view. The BB created the universe..is that? could that? be said to be fallacious if I believed it was say a torus universe?
 
jgweed
 
Reply Sun 21 Feb, 2010 10:03 am
@xris,
xris;130725 wrote:
Surely debates can be allot more subtle than simply correct or incorrect. What if certain knowledge is questionable and you use it, is it fallacious or invalid?


Yes they are subject to different gradations or levels of acceptance ( "tentative conclusions"). Are we not often mislead in our picture of argumentation by using simple examples or translating them into symbolic logic?

Most debates are not as simple as the statement of a categorical syllogism, but tend towards a series of arguments and sub arguments all linked together by one. Moreover, the reasons for accepting premises may vary by subject matter (think of debates about the meaning of an historical text on the one hand, and debates about health care reform on the other).

Many debates center on definitions of terms or on what should be counted as "evidence" or "data" in thinking through a problem (this or that applies). That is to say, the argument at hand becomes one about the nature of argumentation itself.

Sometimes simplification of discussion can be productive, but other times one really needs to consider the subject's complexity or make a list of examples and look for differences and distinctions before one begins to build more general concepts.
 
kennethamy
 
Reply Sun 21 Feb, 2010 10:45 am
@jgweed,
jgweed;130702 wrote:
How do we determine that an argument is "fallacious" (using for the moment a common sense definition of the word to mean incorrect or "wrong")?

There seem to be several criteria for rejecting an argument.

First, The assertions in the premises are either doubtful (without sufficient warrants for accepting them) or wrong (contrary to matters of fact---this does not mean contrary to what I want to believe---and might also include the aspect of credibility).
Second, words in the premises (and/or conclusion) are used in different senses (e.g. the word "bias").
Third, the argument employs informal fallacies. While this might not necessarily make the conclusion wrong, it does put it into question by not providing a sound argument.
Fourth, the formal structure of the argument from premises to conclusion fails to follow logical rules (this can be similar to step 3), or if premises do follow these rules, the logical conclusion may nevertheless be indeterminate.

From the list that of course could be expanded, it seems clear that we accept or reject arguments to a conclusion using more than (strictly speaking) logical tests.





But you are attempting to make a commonsense term into a technical term by setting up conditions for its use, In that case, why not simply accept the logician's sense of "fallacious" which is already a technical term? Why try to reinvent the wheel? In fact, what you seem to be doing is to set up conditions not for a fallacious argument, but for an unsound argument, a condition of which is fallaciousness.

Of course, an argument can be rejected because its premises are false, and indeed, because we know its conclusion is false. If that is what you mean by a not "strictly logical test" you are right.

By the way, the fallacy of begging the question is always possible, but there is some problem in trying to characterize this fallacy correctly. None of your criteria do it.
 
Antoine Roquenti
 
Reply Tue 23 Feb, 2010 01:07 pm
@Deckard,
All members of this forum lie
I lie
therefore........?

for the record, Im not calling the forum-members for liars.
 
xris
 
Reply Tue 23 Feb, 2010 03:27 pm
@Antoine Roquenti,
Antoine Roquenti;131482 wrote:
All members of this forum lie
I lie
therefore........?

for the record, Im not calling the forum-members for liars.
Yes you are, your a liar but im not because your lying.
 
 

 
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