## Friday, June 3, 2016

### Is There A Name For This Logical Error

Everyone is familiar with post hoc, ergo propter hoc, if Y follows X, then X must have caused Y.  In the form promoted by politicians, this is often, "Many crimes use guns, therefore guns cause crime."

I am reading Haag's The Gunning of America right now, which asserts that Colt, Winchester, and Remington created an American gun culture so that they could make money selling guns to people who neither needed nor wanted them.  (You know, like those raging success stories of successful marketing: New Coke, IBM PCjr, and Edsel.)  The problem is the author explicitly says Bellesiles' Arming America was right about this, and she has dug out all the records to prove it.  Now, the paper I just asked you to read proves that X is false; the gun culture well predates these industrial gun companies.  So if X causes Y, but X is false, but you insist Y is true based on X, is there a name for such a logical error, other than Yale History Professor?

3DShooter said...

I believe it is a tautological error.

Anonymous said...

This would be very close to a fallacy known as "affirming the consequent." Not 100% exact, but close. (http://www.logicalfallacies.info/presumption/affirming-the-consequent/)

Also, the broader issues at hand seem to clearly qualify as the "fallacy of the single cause." (https://en.wikipedia.org/wiki/Fallacy_of_the_single_cause)

And the "proof by assertion" (https://en.wikipedia.org/wiki/Proof_by_assertion) is applicable in this case.

But probably the most applicable is the "regression fallacy." (https://en.wikipedia.org/wiki/Regression_fallacy)

If anything, it unsurprisingly seems apparent there are many failures of logic involved in these presented conclusions.

Karl said...

The basic logical error this seems to be is "affirmation of the consequent".
1) If X then Y
2) Y
3) Therefore X *wrong*

In a conditional "if X then Y", you can validly argue that if X is true, Y must be true. X is a sufficient condition for Y. This is called "modus ponens", or "affirmation of the antecedent".

You can validly argue that if Y is false, then X must also be false. This is called "denial of the consequent". In a conditional statement, "if X then Y", the truth of Y is a necessary condition for X to be true. If Y is not true, then X can't be true.

The other two possible combinations of true and false are not valid arguments because they confuse necessary and sufficient conditions.

Affirmation of the consequent fails because the consequent in a conditional statement is not a sufficient condition for the antecedent. Y can be true for any number of reasons other than X being true.

Likewise, denial of the antecedent (if X then Y, X is false, therefore Y must be false) is invalid because Y can result from other sufficient conditions besides X.
So an American Gun Culture (AGC) could have arisen because gun manufacturers created one.
An AGC could have been created by fur traders wanting the cheap supply of animal pelts generated by hunters.
An AGC could have been created by a perceived need to expel British soldiers from the country after declaring independence.
An AGC could have been created by a perceived need for people to defend themselves against hostile animals in unsettled lands.
An AGC could have been created by Martians beaming mind control rays across the North American continent.
All of the last four of these are sufficient conditions for a gun culture to arise even if Colt, Winchester, and Remington had never existed.

Joseph said...

I'm reminded of the net neutrality advocates who are in favor of the current custom of net neutrality and apparently think it was due to regulations that had not yet been passed.

If X then Y.
X.
Therefore Y.

This is valid logic. There is no formal fallacy. However, the argument is unsound if X is not actually true. It would be a false premise.

Karl said...

If X then Y.
X.
Therefore Y.

This is valid logic. There is no formal fallacy. However, the argument is unsound if X is not actually true. It would be a false premise.

That's why you need to distinguish between a valid argument and a true one.
It's easiest in formal logic where the structure of an argument is strictly separate from the content. In formal logic, a valid argument is one where, if the premises are true, the conclusion must be true.

The alert student will note this is another conditional:
If X (the premises are true) then Y (the conclusion is true).
From this conditional, we may validly conclude that if the conclusion is false (not Y), then at least one of the premises must be false (not X).
Formal logic does not guarantee true premises given a true conclusion (affirming the consequent), nor does it guarantee a false conclusion given false premises (denial of the antecedent).

Informal logic, on the other hand, does not have this mathematical precision of definition, and so it's very common to see people labeling as fallacies statements that aren't actually fallacies. For example, the "appeal to authority" is not a fallacy if the authority appealed to happens to be an authority on the matter under consideration. Citing Stephen Hawking in reference to black holes is an appeal to an authority, but a perfectly valid one. Citing Stephen Hawking in arguments about the minimum wage is an invalid appeal to authority.

Anonymous said...

"Citing Stephen Hawking in reference to black holes is an appeal to an authority, but a perfectly valid one."

I respectfully disagree with this statement.

Citing Stephen Hawking, insofar as your only supporting evidence for the existence of black holes is simply because Stephen Hawking says they're so, is a textbook appeal to authority fallacy – expert status or not. To avoid this fallacy, one would need to cite/consider his arguments, reasoning, and evidence – namely, the substance of the position itself – vice the "who" the position originates from. In this way, the authority becomes effectively irrelevant, and the substantive merit of the given position consequently takes center stage, as it should to avoid a failure of logic. It's not about lining up the perceived expert with the appropriate discipline, but rather about not outsourcing your thinking to other people to begin with.

From http://www.logicalfallacies.info/relevance/appeals/appeal-to-authority/

"An appeal to authority is an argument from the fact that a person judged to be an authority affirms a proposition to the claim that the proposition is true. Appeals to authority are always deductively fallacious; even a legitimate authority speaking on his area of expertise may affirm a falsehood, so no testimony of any authority is guaranteed to be true."

The appeal to authority is, in a way, the opposite of the ad hominem insofar as both incorrectly focus on the "who" vice the "what." As just because someone might be a bad person, this conclusion does not make the substance of his/her argument necessarily incorrect, neither does his/her credentials or perceived status as an expert ensure their particular position is actually true. Plenty of experts' positions/theories/opinions turn out to be incorrect (I submit Paul Krugman as just one modern example of this outcome). Indeed, an argument can be made that virtually all modern "hard" science is essentially the process of correcting flawed premises and theories from authorities of yesteryear (ongoing ad infinitum).

Billll said...

This is an appeal to authority. The problem comes in when the authority is questionable as frequently happens.

Karl said...

@keithwarlick:
"Citing Stephen Hawking in reference to black holes is an appeal to an authority, but a perfectly valid one."

I respectfully disagree with this statement.

Then I respectfully point out that you are wrong.
In fact, you're wrong twice.

Citing Stephen Hawking, insofar as your only supporting evidence for the existence of black holes is simply because Stephen Hawking says they're so, is a textbook appeal to authority fallacy – expert status or not.

Minor quibble: I didn't say "existence".
However, Stephen Hawking has studied the nature of black holes, under the assumption that the universe behaves a lot like the math describing it says it does. So if I need to specify, I would cite Hawking on how black holes behave, since he's spent decades building up a store of expertise in the subject.

A more general way in which you have chosen to be quite wrong is, whatever you may think of black holes or Stephen Hawking, the point remains, there are people who are genuine authorities on various subjects, and answers from these authorities can be considered definitive, even in the absence of an absolute guarantee of ultimate truth. If you don't like Stephen Hawking and black holes, the illustration could as easily have been Julia Child and French cooking, or Chief Justice Roberts and the law.
Each of these worthies has considerable expertise in one specific field, and their opinion in that field can be considered authoritative. But Julia Child would not be considered an authority on Law, nor Chief Justice Roberts on black holes, nor Stephen Hawking on buerre blanc. So Julia Child's opinion about the "fragile skull theory" would not carry any weight in a legal discussion.

To avoid this fallacy, one would need to cite/consider his arguments, reasoning, and evidence – namely, the substance of the position itself – vice the "who" the position originates from.

But the point is, Stephen Hawking's credentials are well known. If I cite him in those fields where he has known expertise, I can bypass the step of qualifying him as an expert. The vast majority of reasonable people will readily stipulate to his expertise, and we can move on to the substance. That's the point of calling Hawking an "authority".
So either you are ignorant of Stephen Hawking's career, or you don't understand the concepts underlying informal logic, or you are being deliberately obtuse.

(continued next comment)

From http://www.logicalfallacies.info/relevance/appeals/appeal-to-authority/

"An appeal to authority is an argument from the fact that a person judged to be an authority affirms a proposition to the claim that the proposition is true. Appeals to authority are always deductively fallacious; even a legitimate authority speaking on his area of expertise may affirm a falsehood, so no testimony of any authority is guaranteed to be true."

That an appeal to an authority is always deductively fallacious is true, but meaningless with respect to the study of informal logic. Once we leave the realm of formal logic, we leave behind the mathematical inevitability of logical form.

From the Fallacy Files:
Typically, informal fallacies occur in non-deductive reasoning, which relies on content as well as form for cogency. Also, because content is important in informal fallacies, there are cogent arguments with the form of the fallacy. For this reason, when forms are given in the entries for individual informal fallacies, this is for identification purposes only―that is, one cannot tell from the form alone that an instance is fallacious, since content is also relevant. Rather, the forms will help to differentiate between distinct types of informal fallacy.

(continued next comment)

Karl said...

(continuing from previous comment)

So by cutting off the second paragraph in the text you cited,

However, the informal fallacy occurs only when the authority cited either (a) is not an authority, or (b) is not an authority on the subject on which he is being cited. If someone either isn’t an authority at all, or isn’t an authority on the subject about which they’re speaking, then that undermines the value of their testimony.
You attempted to treat an informal fallacy as if it were a formal one, which is a clear misunderstanding of the plain text you linked.

The Fallacy Files labels this fallacy a bit more clearly as "Appeal to Misleading Authority".

We must often rely upon expert opinion when drawing conclusions about technical matters where we lack the time or expertise to form an informed opinion. For instance, those of us who are not physicians usually rely upon those who are when making medical decisions, and we are not wrong to do so. There are, however, four major ways in which such arguments can go wrong:

1) An appeal to authority may be inappropriate in a couple of ways:
a) It is unnecessary. If a question can be answered by observation or calculation, an argument from authority is not needed...
b) It is impossible. About some issues there simply is no expert opinion...
2) The "authority" cited is not an expert on the issue, that is, the person who supplies the opinion is not an expert at all, or is one, but in an unrelated area...
3) The authority is an expert, but is not disinterested. That is, the expert is biased towards one side of the issue, and his opinion is thereby untrustworthy...
4) While the authority is an expert, his opinion is unrepresentative of expert opinion on the subject....

More concisely, the textbook my mother used in her college class describes:
The ad verecundiam fallacy (appeal to authority fallacy) occurs when one supports a view by appealing to the endorsement of a view by someone who is not in fact an authority on the subject matter being considered.
Fundamentals of Logic; James D. Carney, Richard K. Scheer; The MacMillan Company; 1964

Logic is a fascinating subject; you should study it some time.

Anonymous said...

Lol… I will grant your point regarding the underlying difference between formal and informal fallacy but you also missed the bigger point I was attempting to make entirely. Or, it could easily be that I didn't make it well enough, which if so I can own. In the end, no matter the differences between the logic classes, appealing to an authority – whether arguably valid or not – does not in any way make a given position empirically correct.

However, it's apparently far more personal for you than for me, and suffice it to say we're entitled to our own opinions, so have a great day.

Clayton Cramer said...

Appealing to authority means it will survive peer review. It may still be wrong!