A Magical Journey through the Land of Logical Fallacies - Part 2
The second part of our exploration of logical fallacies.
Filed under Logic & Persuasion
| Skeptoid #74 November 13, 2007 Podcast transcript | Listen | Subscribe Also available in Greek |
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Today we're going to continue with the second part of our exploration through the jungle of logical fallacies, so sharpen up your machete and follow me as we hack and chop our way through all of this mess. If you haven't heard last week's episode, we covered many of the most common logical fallacies and other argumentative devices that are commonly used by proponents of something that can't otherwise be supported by evidence, like many pseudosciences and conspiracy theories. Hopefully, familiarity with these devices will help you to identify them in conversation. And, when you point them out, you often strip your opponent of the tools on which he depends the most. If you're going to have a debate, stick with valid arguments. Don't get caught out by fallacies.
We finished up last week with post hoc rationalizations and slippery slope arguments. And we will now continue with:
Excluded Middle
The excluded middle assumes that only one of two ridiculous extremes is possible, when in fact a much more moderate middle-of-the-road result is more likely and desirable. An example of an excluded middle would be an argument that either every possible creation story should be taught in schools, or none of them. These two possibilities sound frightening, and may persuade people to choose the lesser of two evils and allow religious creation stories to be taught alongside science. In fact, the much more reasonable excluded middle, which is to teach science in science classes and religion in religion classes, is not offered.
The excluded middle is formally called reductio ad absurdum, reduction to the absurd. Bertrand Russell famously illustrated how an absurd premise can be fallaciously used to support an argument:
Starling says: "Given that 1 = 0, prove that you are the Pope."
Bombo replies: "Add 1 to both sides of the equation: then we have 2 = 1. The set containing just me and the Pope has 2 members. But 2 = 1, so it has only 1 member; therefore, I am the Pope."
Just keep in mind that if your opponent is presuming extremes that are absurd, he is excluding the less absurd middle. Don't fall for it.
Statistics of Small Numbers
You really have to take a statistics class to understand statistics, and I think the part that would surprise most people is the stuff about sample sizes. Given a population of a certain size, how many people do you have to survey before your results are meaningful? I took half of a statistics class once and learned just enough to realize that practically every online poll you see on the web, or survey you hear on the news or read about in the newspaper, is mathematically worthless.
But it extends much deeper than surveys. Drawing conclusions from data sets that are too small to be meaningful is common in pseudoscience. Listen to Bombo make a couple of bad conclusions from invalid sample sizes:
"I just threw double sixes. These dice are hot."
"My neighbor's a Mormon and he drinks wine, so I guess most Mormons don't really follow the no-alcohol tradition."
"I went to a chiropractor and I feel better, so chiropractic does work after all."
Weasel Words
Giving a controversial concept like creationism a new, more palatable name like Intelligent Design is what's called the use of weasel words. Calling 9/11 conspiracies "9/11 Truth" is a weasel word; clearly their movement has nothing to do with truth, yet they give it a name that claims that's what it's all about.
Weasel words are a favorite of politicians. Witness the names of government programs that mean essentially the opposite of what they're named: the Patriot Act, No Child Left Behind, Affirmative Action. By the way certain programs are named, it sounds like it would virtually be criminal to disagree with them.
Weasel words can also refer to sneaky wording in a sentence, like "It has been determined", or "It is obvious that", suggesting that some claim has support without actually indicating anything about the nature of such support.
Fallacy of the Consequent
Drawing invalid subset relationships in the wrong direction is called the fallacy of the consequent. Cancers are all considered diseases, but not all diseases are cancers. Stating that if you have a disease it must be cancer is a fallacy of the consequent.
Listen to how Bombo blames Starling's failure to heal upon his failure to take one particular treatment, without regard for whether that treatment is a valid one for Starling's particular condition:
Starling: "I am dying of bubonic plague."
Bombo: "You did not drink enough wheatgrass juice."
Even assuming that wheatgrass juice was a suitable treatment for anything, it would still not be a suitable treatment for everything, so Bombo's suggestion that Starling's illness is a fallacious consequence for his failure to drink wheatgrass juice.
Loaded Question
A loaded question is also known as the fallacy of multiple questions rolled into one, or plurium interrogationum. If I want to force you to answer one question in a certain way, I can roll that question up with another that offers you two choices, both of which require my desired answer to the first question. For example:
"Is this the first time you've killed anyone?"
"Have you always doubted the truth of the Bible?"
"Is it nice to never have to hassle with taking a shower?"
Any answer given forces you to give me the answer I was looking for: That you have killed someone, that you doubt the truth of the Bible, or that you don't shower or bathe. Loaded questions should not be tolerated and certainly should never be answered.
Red Herring
A red herring is a diversion inserted into an argument to distract attention away from the real point. Supposedly, dragging a smelly herring across the track of a hunted fox would save him from the dogs by diverting their attention away from the real quarry. Red herrings are a favorite device of those who argue conspiracy theories:
Starling: "Man landed on the moon in 1969."
Bombo: "But don't you think it's strange that Werner von Braun went rock hunting in Antarctica only a few years before?"Starling: "9/11 was perpetrated by Islamic terrorists."
Bombo: "But don't you think it's strange that Dick Cheney had business contacts in the middle east?"
Red herrings are fallacious because they do not address the point under discussion, they merely distract from it; but in doing so, they give the impression that the true cause lies elsewhere. The wrongful use of red herrings as a substitute for evidence is rampant, absolutely rampant, in conspiracy theory arguments.
Proof by Verbosity
The practice of burying you with so much information and misinformation that you cannot possibly respond to it all is called proof by verbosity, or argumentum verbosium. To win a debate, I need not have any support for my position if I can simply throw so many things at you that you can't respond to all of them.
This is the favorite device of conspiracy theorists. The sheer volume of random tidbits that they throw out there gives the impression of their position having been thoroughly researched and well supported by many pillars of evidence. Any given tidbit is probably a red herring, but since there are so many of them, it would be hopeless (and fruitless) to respond intelligently to each and every one of them. Thus the argument appears to be impregnable and bulletproof. It may not be possible to construct a cogent argument using proof by verbosity, but it is very easy to construct an irrefutable argument.
Poisoning the Well
When you preface your comments by casually slipping in a derogatory adjective about your opponent or his position, you're doing what's called poisoning the well. A familiar example is the way Intelligent Design advocates poison the well by referring to evolution as Darwinism, as if it's about devotion to one particular researcher. Or:
"And now, let's hear the same old arguments about why we should believe UFOs come from outer space."
"Celebrity television psychic Sylvia Browne tells us in her new book."
If you listen to this podcast, you know that I poison the well all the time. It's one of my favorite devices. But I do it obviously, for the entertainment value, and not as a serious attempt at argument.
Bandwagon Fallacy
Also known as argumentum ad populum (appeal to the masses) or argument by consensus, the bandwagon fallacy states that if everyone else is doing it, so should you. If most people believe something or act a certain way, it must be correct.
"Everyone knows that O.J. Simpson was guilty; so he should be in jail."
"Over 700 scientists have signed Dissent from Darwin, so you should reconsider your belief in evolution."
The bandwagon fallacy can also be used in reverse: If very few people believe something, then it can't be true.
Starling: "Firefly was a really cool show."
Bombo: "Are you kidding? Almost nobody watched it."
Consider how many supernatural beliefs are firmly held by a majority of the world's population, and the lameness of the bandwagon fallacy comes into pretty sharp focus. The majority might sometimes be right, but they're hardly reliable.
That concludes our look at logical fallacies. There are certainly many others, but these are the big ones and then some, and most of the others are just subcategories of some of these. Learn these fallacies, and become handy with them. You'll find that you can easily recognize them in almost every argument someone makes, and then you're well equipped to stop them in their tracks, and require them to instead make a non-fallacious argument. Doing so strips away the bulk of the meat from the arguments of most people who advocate things that aren't evidence-based, and places you handily in a commanding position.
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© 2007 Skeptoid Media, Inc. Copyright information
References & Further Reading
Kahane, Howard; Cavender, Nancy. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life. Belmont: Thomson Higher Education, 2006. 155-156.
Morier, Dean; Keeports, David. "Normal science and the paranormal: The effect of a scientific method course on students' beliefs." Research in Higher Education. 1 Jul. 1994, Volume 35, Number 4: 443-453.
Porter, Burton Frederick. The Voice of Reason: Fundamentals of Critical Thinking. New York: Oxford University Press, 2002.
Sagan, Carl; Druyan, Ann. The Demon-Haunted World: Science as a Candle in the Dark. New York: Random House, Inc., 1996.
Urdan, Timothy C. Statistics in Plain English. Mahwah: Lawrence Erlbaum Associates, Inc., 2005.
Walton, Douglas. Informal Logic: A Pragmatic Approach. New York: Cambridge University Press, 2008.
Reference this article:
Dunning, Brian.
"A Magical Journey through the Land of Logical Fallacies - Part 2." Skeptoid Podcast. Skeptoid Media, Inc.,
13 Nov 2007. Web.
10 Sep 2010. <http://skeptoid.com/episodes/4074>
Discuss!
Remember, you should always read with skepticism the comments of anyone too lame to put their real name & city.
Kudos to Brian for recognizing his own fallacies.
Hippies are a favorite foil! Nobody likes a hippie.
I recently saw Penn and Teller's BS on "Nukes, Hybrids and Lesbians" (BTW, everthing that Teller says on that program is the Gospel Truth! I swear. ;)
Of course Penn liberally poisons the well all the time on BS. I think it makes it fun to watch. The long-haired Penn called the anti-nuke guy a "hippie" even though he had short hair and wore normal clothes. Still, it felt right.
Tim, Yokohama, Japan
November 15, 2007 12:12am
I second Robert's comments. As I understand it, the following argument illustrates reductio ad absurdum:
If not A, then A. Not A; therefore A.
Sometimes the following argument is also referred to as reductio ad absurdum:
If A, then not A. A; therefore not A.
Shayne, Oxford, MA, USA
November 15, 2007 4:35am
Tim: I concur. Kudos to Brian for acknowledging his own fallacious argumentation techniques...after they’re pointed out to him!
Shayne: You're on the right track here. Technically, the arguments you provide are instances of what's called 'modus ponens', but they’re pretty closely related. Here's an example of reductio argumentation:
1. Assume A.
2. Demonstrate that from the assumption that A, it follows that not A.
3. Conjoin A and not A.
4. It follows from the law of non-contradiction that the conjunction of A and not A is false.
5. Therefore, since a falsehood (namely, a contradiction) was derived from the assumption that A, A must be false.
We find classical reductio reasoning in Plato and Aristotle all the time. For example, in ‘The Republic’, one of Socrates' interlocutors proposes a definition of justice as the "advantage of the stronger". Socrates proceeds to demonstrate (or so he believes) that if we assume that justice is, in fact, the advantage of the stronger, it follows that justice is also what is *not* to the advantage of the stronger. Since Socrates has derived a contradiction from the original assumption (that justice is the advantage of the stronger), it follows (or so Socrates claims) that this original definition of justice must be false.
And all that without ad hominem attacks or even “Poisoning the Well”. Imagine that! (Though I doubt whether Socrates would have ever had a successful or “entertaining” podcast!)
Cheers!
Robert, New Haven
November 15, 2007 11:08am
Weasel words could include:-
Sellafield....aka WINDSCALE!
Boom Boom ....
neil griffiths, Cardiff uk
November 16, 2007 3:16pm
Thanks for clarifying, Robert. You obviously know this stuff better than I.
I'm used to thinking of modus ponens as a rule of logic rather than a specific type of argument. Doesn't modus ponens occur implicitly in your statement #5 above?
Shayne, Oxford, MA, USA
November 18, 2007 5:16am
Mmmm.... latin.
Marius vanderLubbe, Nullabour Plain, Ausrtalia
November 19, 2007 1:16am
Hey Shayne,
Actually, modus ponens is both a specific type of argument and a "rule" of propositional logic (sometimes referred to as a 'rule of inference'). And as I said, modus ponens and reductio are closely related. In (5) above, you can think of that as a form of modus ponens in the following sense:
P1. If I derive a contradiction from the assumption that A, then A is false.
P2. I have derived a contradiction from the assumption that A.
C. Therefore, A is false.
Reductios are used in formal logic and mathematics in what are called 'indirect proofs'. That's kinda what I did above only less formally.
Cheers,
-R
Robert, New Haven
November 19, 2007 12:15pm
A couple of points. First, an expansion on weasels; second, another common rhetorical technique: the Gambit.
Weasels are damage-reducers, and they are frequently seen in advertising blurbs, as in "helps fight cavities." Advertisers do not like being sued for making outright false claims, so they prefer to weasel out wherever possible. In this example, we see two weasel words: "Helps" and "Fight." The implied claim is that Substance X reduces the likelihood of tooth decay, but they can't actually SAY that outright. So they use nebulous words like "fight." "Fight" is a nebulous word with little or no meaning in the context. Then, to doubly insulate themselves, the writers insert "Helps."
The Gambit is similar to the card-game concept of losing your losers first. If your position has a weak spot, concede it early and make yourself look fair-minded.
Dave, Rocket City, AL
December 05, 2007 11:27am
You left out argument of the beard. That is a good one and it comes up quite often.
dogcow, tampa
February 26, 2008 5:14pm
What is it called when someone simply refers to the other as "close minded" for not being able to see the "obvious" correct answer? As in, "Those that believe in evolution are just closed minded people unwilling to see the truth."
It seems like it would be a close relation to the, "You're wrong because you're an idiot." argument.
Rob E., Memphis, TN
February 29, 2008 6:49pm
Rob,
Calling someone 'closed minded' isn't a fallacy. People may or may not actually BE closed minded.
If someone is refusing to except good evicence (which both wackoes and skeptics migth be guilty of) then they ARE closed minded.
If the evidence actually ISN'T good, then I'd say calling someone closed minded is a red herring, or perhaps an ad hominem.
Morgan Z., Tracy, CA
August 29, 2008 12:57pm
There are a few more kinds of logical fallacy that you forgot to include, but I hesitate to mention it because I'm not sure how to say it. Fortunately, I guess, my mother is nowhere near as hesitant, and claims I must put it here for all to see.
Conclusions about conclusions:
Simply put, it is all too easy for one to claim that an position is incorrect just because the arguements supporting it are invalid. As a case in point: garlic for various sicknesses had for centuries been considered just an old-wives tale, because none of the old wives in question had been able to generate formal scientific evidence to back their tales up. Imagine the medical community's surprise, then, when garlic was studied and discovered to be an immune-system booster for all kinds of different reasons (I think at last count they'd found fifty-four different immune boosting chemicals...and the figure was still rising). Yes, the old wives had been correct--but this was something the scientists may have known much sooner had they tested the claims, instead of simply rejecting the conclusion out of hand because the arguements were bad.
Anti-Fallacy:
It is possible to make a logical fallacy not just logical, but necessary.
Money is a prime example of this--it is worth nothing inherently, and it is backed by nothing more than a complete red herring...but because everybody believes it is worth something, hey, it is. Reasonable? No. Real? No. Logical? In a weird way, yes.
Bill L, Midlothian, VA
September 10, 2008 1:45pm
I want to correct an error in this podcast. Excluding the middle is not formally called reductio ad absurdum, they're different (though somewhat related). Reductio ad absurdum is not a logical fallacy, but a perfectly valid argument which originated in mathematics as a method to invalidate a theory or equation.
It's the process of finding a contradiction to a stated claim, since any contradiction of the claim invalidates it. Specifically, it's reducing a claim to an absurd case which proves the claim false.
An example of reductio ad absurdum is the irreducible complexity argument from intelligent design. By finding a single organism, no matter how absurd, which could not have evolved they would indeed prove that evolution didn't create all life. Irreducible complexity is wrong not because it's a logical fallacy but because they have not been able to find any such organism. The logic, however, is sound.
Adam, Gold Coast, Australia
December 25, 2008 6:02pm
Listening to these episodes I could not help but thinking about a movie called "Thank You for Smoking" (link below). This movie is a display in how good rhetorical skills can advocate the worst of opinions.
Keep up the good work with the podcast!
http://www.imdb.com/title/tt0427944/
David, Borås, Sweden
April 06, 2009 10:52am
Being fallacious and yet logical?
Logical fallacy = oxymoron.
Joe Boudreault, Hanover, Ont, Canada
May 07, 2009 4:54am
Good work, Joe.
I know a better one.
Creation Science.
Marius vanderLubbe, Nullabour plain, Australia.
July 21, 2009 1:43am
Besides the mistakes Robert gave, you also got the definition of "weasel words" wrong. Giving something an innocuous name isn't a "weasel word", they're words like "may" or "might" etc that allow you to claim anything while retaining an escape route in case you're wrong.
Simon, Seattle
October 08, 2009 4:12pm
Yes, I know, old episode is old, but.
Joe: "Logical Fallacy" means that the logic used is fallacious.
Bonus question: Which fallacy is Joe using by trying to play semantics?
Chris, Greensburg, PA
November 19, 2009 5:12am
"My neighbor's a Mormon and he drinks wine, so I guess most Mormons don't really follow the no-alcohol tradition."
"I went to a chiropractor and I feel better, so chiropractic does work after all."
Do statistical fallacies differ in any qualitative way from the anecdotal fallacies? Isn't a statistically meaningless survey the same as a collection of anecdotes?
Mark, Cincinnati
March 17, 2010 8:23pm
Not necessarily. My old rhetoric professor advised us to set up 2x2 Tables, as he called them. The X axis was one set of criteria (say, one column is Go To Chiropractor, the other is Didn't Go), and along the Y axis is the other (one row is Felt Better, the other is Didn't). You put a dash in the appropriate box every time you find a datum. So if you feel sick, don't go to the chiropractor, and feel better, you put a tickmark in the "Didn't Go, Felt Better" box.
Over time, you'll notice trends. For example, if almost all the tickmarks are in the "Felt Better" row, and evenly distributed between "Went To Chiropractor" and "Didn't go" colums, you can start to rule out chiropractic as a viable treatment method.
It's still anacdotes, because it's not a valid survey, but it's more rigerous because it forces you to acknolwedge the misses as well as the hits, and it gives you a better back-of-the-envelope understanding of the phenomenon in question.
Gregory, Alabama
April 30, 2010 9:35am
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Glad to hear you acknowledge that you often argue fallaciously (for “entertainment” purposes).
Regarding “Excluded Middle”, it is not "formally called reductio ad absurdum", but is actually formally called 'False Dichotomy' (or 'False Dilemma', or 'Bifurcation'). Though 'reductio' is used to describe a kind of informal fallacy (not in your sense), reductio arguments are, strictly speaking, valid deductive arguments that rely on the law of non-contradiction to demonstrate the truth of a conclusion by deriving a formal contradiction from an assumption. There is a sense of 'reductio ad absurdum' that means something like, "Your point is so obviously absurd, that the view you're arguing for must be false". I suppose that would make it a *kind* of “fallacy”. However, it’s not, as you claim, (necessarily) the same thing as “Excluded Middle”.
As to the Russell case, he was actually addressing the somewhat counterintuitive truth-function of the material conditional wherein a false antecedent yields a true statement, regardless of the truth-value of the consequent. Though importantly connected to the formal reductio, it has little to do with the informal sense in which you describe the "fallacy" of reductio or with the “Excluded Middle” fallacy.
Lastly, the term ‘Excluded Middle’ is used in logic mostly (if not exclusively) to refer not to a fallacy, but to a law of classical logic wherein every statement (or ‘proposition’ (depending on your metaphysics)) is either true or false.
Robert, New Haven
November 14, 2007 11:46am