Fallacies on fallacies

Many people are confused about what counts as a fallacy, including teachers of critical reasoning. Opponents of science often accuse pro-science writers of "the fallacy of authority" or "the ad hominem fallacy" when they are noted for having made silly and false claims before. I thought some words about what a fallacy actually is might be to the point.

According to Archbishop Richard Whately, whose book The Elements of Logic, first published in 1828 from an encyclopedia article revitalised the modern study of logic in the English tradition,

By a Fallacy is commonly understood, "any unsound mode of arguing, which appears to demand our conviction, and to be decisive of the question in hand, when in fairness it is not."

Basically, a fallacy is something designed to lead the hearer or reader to draw the wrong conclusion.

H. W. B. Joseph's Introduction to Logic, which is still a classic and available at archive.org, has a few things worth reading about authority:

But because we have constantly to appeal to the conclusion of a previous process of demonstration or other reasoning without rethinking that process at the time, we are constantly syllogizing ; and where the premisses are such of which we remember to have previously satisfied ourselves by reflection or demonstration or inductive argument, or (if they concern facts established by authority) by reference to authority, there syllogism may deserve the name of proof. [p311]

The schoolmen knew, as well as Bacon or any other of their critics, that the study of the syllogism was not all-sufficing: that no syllogism could guarantee the truth of its premisses; and that for a knowledge of the most general principles to which deductive reasoning appeals we must rely on something else than deductive reasoning itself. Bacon refers to the 'notorious answer' which was given to those who questioned the accepted principles of any science --- Cuique in sua arte credendum.* And there are seasons in the process of learning when that is a very proper answer; men must be content at many times and in many matters to accept the expert opinion of their day. But this is only tolerable if in every science there are experts who are for ever questioning and testing. When tradition stereotypes doctrine, it is as bad for knowledge as close guilds and monopolies are bad for the industrial arts; they shut the door upon improvement. Authority plays, and must play, a great part in life --- not only in practice, but also in things of the intellect. But the free spirit is as necessary, which insists on satisfying itself that what is offered upon authority has claims on its own account upon our acceptance. [p376]

Appeal to authority is not fallacious, so long as the authority cited is relevant and reliable. A principle known as the division of cognitive labor (I think due to Hilary Putnam) suggests that we literally must rely on authorities in the absence of time, resources and cognitive capacities to rerun all experiments and observations since the beginnings of science and history. What is a fallacy is appeal to authority to make the listener conclude things that do not follow, either because the authority is unreliable or inappropriate, or because the authority is now known to be wrong (e.g. the constant quote mining of older biologists by creationists).

Likewise, ad hominem (the use of insult) is not a fallacy unless it is designed to mislead the listener. There is nothing wrong with calling someone who is a thief a thief. But if you do this in order to mislead a jury about his testimony against another criminal, that is a fallacy. Testing his testimony is something one does with evidence and reasoning. If he is a habitual liar, it is ad hominem ("to the man") to bring that up; it is not fallacious, because that really does call his testimony into question.

Many things are said about fallacies on the internet these days which show a complete ignorance of the underlying principles of reasoning on which they are based. In my opinion, a fallacy is exactly what Whately said it was back in 1827 or so: something which demands our conviction which does not establish it. This definition goes back at least to Locke's discussion of fallacies in Book IV, chapter XVII of his Essay.

There is no canonical list of fallacies because there are an indefinite number of ways to be wrong, but the division is conventionally made into fallacies of form and fallacies of rhetoric. Fallacies of form are mistakes in actual logic; rather like mistakes of arithmetic or mathematics. Fallacies of rhetoric are fallacies of how ideas are "sold", such as the use of statistics or mathematics to mislead rather than elucidate. Politicians, when faced with data they do not like, usually engage in fallacies of rhetoric; however, they also make egregious mistakes of logical reasoning (the most common being the fallacy of affirming the consequent, in my opinion).

Go download Joseph and read bits of it at night. It is well worth it. Yes, there are modern texts you can get, but that all lack that magisterial tone that really commands attention (oops, I think that might be a fallacy).

Some links:

*“Each person is to be believed with regard to his own specialty”, from Bacon's The Advancement of Learning, Book II. This is a legal principle as well.

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Having had one course in the philosophy of logic and language (my God what is it with philosophers and Frege, get over him allready!), I have a little knowledge about syllogisms and arguments, however flawed.

And I constantly run into exactly the ad hominem charge being used incorrectly.

It'll go like this:

a: The bible is tue, because God says so
and God cannot lie, according to the bible, so there!

b: You fucking nitwitt, what a stupid argument. You are just running around in circles, chasing your own tail. To assert the truth of a text, based on the claims of that same text is no kind of logical excepted by anyone with two functioning braincells.

a: Wah Wah, you used an ad hominem fallacy, I'm telling maw

In this made up example, respondent b uses insults, states his subjective opinion, and argues against a point made by a.

But in fairness, while the reply is perhaps to rough and disrespectful, it is not a fallacy. The harsh words point directly to the fallacy committed by a, and identifies the underlying problem with it.

It is poor debating style, but its not

"an unsound mode of arguing, which appears to demand our conviction, and to be decisive of the question in hand, when in fairness it is not."

Spot on with regard to your definition of a fallacy. Put in simpler language - a fallacy is claim that is not justified or an argument that has gone wrong.

And as you rightly point out, something is not a fallacy just because it seems like one. This, I think, is one of the hardest things for people to differentiate. Calling someone an idiot is only fallacious if that's the basis of your argument. E.g., "The type of home insurance recommended by Andy is wrong because he's an idiot." Andy may indeed be an idiot; however, he might (even if by chance) be recommending a home insurance policy that meets your needs exactly.

Whereas the following is not fallacious even though you are still calling Andy an idiot: "Andy is an idiot because he has recommended you get home insurance that doesn't cover you for a fire, and fire cover is essential in any home insurance policy."

I.e., you are saying Andy is an idiot because his claim is wrong, not his claim is wrong because he is an idiot.

Here�s a post I did that specifically addresses this type of thing with Begging the Question:

Thank John,not only for the post but also the provided links.

English is my second language so Im still trying to get through the relevant literature there...
As a veteran of the Cracker wars I have come across most of the fallacies by now,and the Crackergate threads are a marvellous place to go and exercise your skills in detecting them !

Interesting post. However, I do wonder if the emphasis on logical argument is itself a little mistaken. The problem is that almost nothing that is debated by non-mathematicians has a definitive proof or disproof. Instead, on most issues, the best we can do is something along the lines of "the predominance of evidence supports X versus Y". Of course, reasoning in terms of evidence is actually more difficult than pure logical reasoning, so if people get logic screwed up, then what hope is there for getting evidentiary reasoning right?

Even though almost nothing debated outside mathematics (more generally, the formal sciences) allows for definitive proof or disproof, it's quite common for those debates to include arguments where the conclusions are presented as "logically following from" various premises. The logical validity of such sub-arguments, and their ramifications for the broader debates, is fair game for critics.

By bob koepp (not verified) on 22 Sep 2008 #permalink

a: The bible is tue, because God says so
and God cannot lie, according to the bible, so there!

That is not so. Genesis 2:17 presents an example of God lying.

By Kalia's little… (not verified) on 22 Sep 2008 #permalink

If I may I would like your judgment on this argument.
There is a book called The Wimp Factor: Gender Gaps, Holy Wars, and the Politics of Anxious Masculinity in which the author claims the American electorate is the throws of a condition he calls femiphobia.
The author claims to have gathered data from various sources, including his own research, and from those data came to this conclusion.
I disagree with his conclusion as it discounts the traditional role of the leader in patriarchal societies as the supreme warrior and chief judge (wise father). Those roles can easily explain the occurrence of displays of "manliness," i.e., posturing as with a weapon, saber rattling, and other aggressive behavior. Instead he chose to create a new system of beliefs out of whole cloth.
My arguments against him are these:
No reputable journal chose to review his text. If his findings were of such quality, someone would have chosen to review this book as its claims are quite extraordinary.
The author has no publishing record. Even if he is in private practice, I expect the norm to be publish in a journal one or two articles and so establish a critical audience and response. Private practice does not preclude peer review. As a former engineer, our company gave bonuses to employees who were published in respected journals.
The author as a psychologist, deliberately chose to use the term "phobia," which correct or not implies mental illness. This action indicates to me that his intent is not to educate or elucidate rather to popularize, i.e., sell more books. By painting the opposition as mentally ill, suffering from a delusion or irrational fear, he deploys an ad hominem fallacy against a whole swath of the population.
I argue the author is incredible and an unreliable authority based on the the above criteria. Others contend that the lack of citations to his work (there are few and only in obscure journals) does not mean studies are not ongoing. While that may be true, it doesn't necessarily mean the author is the instigator of those inquiries. They claim I do not understand the publishing and research methodology of the field. (That is true; however, if it is that easy to gain authority in the field, I wonder if it in itself is credible.)
In turn I am accused of ad hominem because I point out the author misuses the clinical term, (and I believe deliberately so) and as such his intentions undermine the argument, i.e., I accuse a charlatan of being a charlatan. I did not couch in in those words, I simply stated he has the same credibility as a nganga, using anecdotal data to describe a broad condition.
I would value your opinion on this discussion. I'm more curious if we should hold those who know better to a higher standard - namely not to misuse terms such as phobia or theory - or whether in their efforts to educate the general public it is acceptable to lower the standard. The frau (herself a MD/PhD) thinks I can be too inflexible on these matters, but I see them as the beginning of the slippery slope. Thank you.

By Onkel Bob (not verified) on 22 Sep 2008 #permalink

You say that one of the most common logical fallacies committed by politicians is affirming the consequent, but isn't it true that this is only fallacious deductively speaking? Scientists, as you know, commit this "logical fallacy" every day with the hypothetico-deductive method, and its saving grace is the fact that the theories are defeasible.

So with that said, and knowing the politicians are rarely speaking strictly of analytical truths and are concerned with empirical reality, I don't think it's too much of a criticism to argue that they affirm the consequent. As another commenter said above, I think the obsession with deductive validity is given way too much emphasis when we clearly live in a world best understood by fallible epistemologies that admit of potential mistakes. None of us are going to attain Godhood here!