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June 23rd, 2006 (Permalink)

Blurb Watch: Nacho Libre

Here's a blurb from an ad for the new Jack Black movie "Nacho Libre":

AP Associated Press
Christy Lemire

If that's true, then why does she give the movie a rating of only two and a half stars out of four? Reading the blurb taken out of context, you naturally assume that the first word―"it's"―refers to the movie. But if you read the entire review, it's clear that it does not refer to the movie as a whole, but to a song that Jack Black performs in the movie. Beware the dangling pronoun!

Source: Christy Lemire, "At the Movies: `Nacho Libre'", Associated Press, 6/14/2006

June 22nd, 2006 (Permalink)

Check it Out, Too

The latest "Skeptic" column by Michael Shermer in the most recent issue of Scientific American concerns confirmation bias―that is, the tendency of people to seek, attend to, and remember evidence that supports their preconceptions and to avoid, not notice, and forget evidence that contradicts them. The problem that I discussed in the previous entry is a specific type of confirmation bias which afflicts fallacy hunters. Shermer discusses the use of functional magnetic resonance imaging to study the brains of people dealing with confirmatory and disconfirmatory evidence. I don't know enough to evaluate the quality of the research, but it's certainly interesting. Unfortunately, the column is not yet available online, so if you're in a hurry to read it you'll have to find a paper copy of the magazine.

Resource: Robert Todd Carroll, "Confirmation Bias", The Skeptic's Dictionary, 2/13/2006

June 20th, 2006 (Permalink)


On its tenth anniversary, Eugene Volokh gives Slate some good advice about how to correct "Bush Contextomies of the Day", and other errors. It's nice of Slate to solicit criticism on its anniversary, but I suspect that it will have about as much effect as most people's New Year's resolutions. Volokh has been criticizing Slate for years, and the editors clearly know about it, but many of the same problems continue. Why should they turn over a new leaf just because it's their tenth anniversary, which is an artefact of our base ten numbering system?

The following paragraph reminded me of a problem with a different type of error correction:

The harms caused by excessive prosecutorial zeal are of course greater than the harms caused by excessive journalistic zeal, especially in the lighthearted field of poking fun at politicians' foibles. Still, journalists, like prosecutors, may lose a necessary sense of perspective and fairness if they set their agenda to be "Let's find something that X did wrong," rather than "Let's find something that someone did wrong, whoever that someone might be."

Too often, fallacy hunters set out to find fault with the arguments of those whom they disagree with, and whose conclusions they want to reject, instead of looking for flaws in their own arguments and those whose conclusions they wish to believe. In this way, looking for fallacies becomes a way of reinforcing prejudices, rather than correcting errors and strengthening arguments, as it should be.

Source: Eugene Volokh, "What's Wrong With Slate: And three ways to fix it", Slate, 6/19/2006

June 13th, 2006 (Permalink)

Puzzle: The Ice Cream Diet

A calorie is by definition the amount of heat it takes to raise 1 gram of water by 1 degree Celsius. A gram of fat contains around 9 calories. Ice cream is primarily fat, since it is made out of cream, so it will have 9 calories per gram―or less, since carbohydrates and protein have fewer calories per gram than fat, and most ice cream has sugar and flavorings. Also, since ice cream is frozen, it is at approximately 0 ° C when you eat it, so that your body must supply the heat to raise the temperature of the ice cream to body temperature. Since human body temperature is approximately 37 ° C, the temperature of the ice cream must be raised 37 degrees.

Therefore, your body must use 28 more calories in heating the ice cream up to body temperature than are contained in the ice cream itself. So, you can lose weight by eating enough ice cream as a dessert with every meal to compensate for the calories that you have consumed in the previous courses. Simply calculate how many calories are contained in the courses before the dessert, then determine how many grams of ice cream you need to eat to burn up those calories. And, if you want a little more ice cream on top, don't feel guilty! You're burning up 28 calories with every chilly, delicious gram you eat!

What's wrong with this reasoning?


June 12th, 2006 (Permalink)

The Etymological Fallacy

Reader Topher Cooper wrote in to suggest a fallacy for the files, namely, the "etymological" fallacy, which is the mistake of taking the etymology of a word to reveal its meaning. The etymological fallacy, as usually described, seems to be a mistake in semantics rather than in reasoning. Moreover, the only writer on logical fallacies that I can find who discusses it―under the name "abuse of etymology"―is Robert Gula in his book Nonsense, which has the longest list of fallacies in a single book that I'm aware of―though longer isn't necessarily better!

However, Topher suggested that the etymological fallacy might be a type of equivocation, which is plausible. Gula lists "abuse of etymology" as a type of misleading appeal to authority―I assume that the authority supposedly appealed to is past usage―but the cooked-up example that he gives seems to be an equivocation. At the least, abuse of etymology is a logical boobytrap, since it could lead someone to commit an equivocation.

So, the etymological fallacy is plausibly a mistake in argumentation, but one question remains to be answered before endorsing it as a logical fallacy: is it a common type of error? Some philosophers seem inordinately fond of etymology, but I hesitate to accuse them of committing fallacies―they're pretty touchy! As usual, I will end with an appeal to the reader to send me examples if you know of any!


June 5th, 2006 (Permalink)

What is Called Critical Thinking?

I don't use the term "critical thinking" much because it's so vague and ambiguous that just about anything can be―and is―called "critical thinking". Of course, the study of logical fallacies is usually considered part of "critical thinking", and I'm all for that, and to that extent I favor "critical thinking". However, a little critical thinking about "critical thinking" reveals that it is a concept with such ill-defined and shifting boundaries that it isn't very useful for thought, critical or otherwise. Howard Gabennesch makes a similar observation at the beginning of an article in the Skeptical Inquirer:

When republic is used in such expressions as "The People's Republic of ____" or lies refers reflexively to an adversary's interpretation of the facts, damage is done to the concepts―liberal government, truthfulness―that stand behind the words. Critical thinking is another concept whose value is being diminished by terminological disarray.

A rousing start, but I was disappointed in not finishing the article with a better understanding of "critical thinking". I do like Gabennesch's use of the phrase "intellectual due process":

Like the honest juror, the critical thinker is ethically committed to the concept of due process―intellectual due process―as the best way to increase the likelihood of finding the truth. This code of intellectual conduct demands giving ideas their day in court before rendering an informed and reasoned verdict.

The concept of "intellectual due process" might be more useful than "critical thinking", at least if the steps in the process were spelled out. Unfortunately, Gabennesch does not develop the idea, instead emphasizing the ethical commitment of the critical thinker to "intellectual due process" without explaining exactly what it is one is committed to doing.

Gabennesch ends the article with an appeal to "skeptics" that I can wholeheartedly second:

We should avoid concentrating our skepticism too narrowly on the realms of superstition, pseudoscience, and the supernatural―for the ultimate challenge to a critical thinker is posed not by weird things but by insidiously mundane ones. If we hope to realize the promise of critical thought, it is important that skeptics affirm a multidimensional definition of critical thinking…that exempts no aspect of social life.

Source: Howard Gabennesch, "Critical Thinking: What Is It Good for? (In Fact, What Is It?)", Skeptical Inquirer, 3-4/2006

June 3rd, 2006 (Permalink)

Check it Out

Carl "The Numbers Guy" Bialik's latest column deals with the efforts of the American Association for Public Opinion Research to do something about problem polls, and the press that loves them. He mentions some of the common problems with polls:

Faulty survey data takes many forms. Sometimes the questions are loaded, as with a survey about online gambling I wrote about in April. Other surveys have very low response rates, like a poll about the value of mothers' work; or pollsters don't disclose all of their questions nor results, raising fears they've cherry-picked those responses that reflect best on the polls' sponsors. Also, many polls you may read about have been conducted online, usually among a panel of volunteers lured by online ads―considered a less-representative sample by most pollsters than respondents who are found by random-digit telephone dialing.

See his discussion of the recent American Medical Association spring break poll for an extended example.

Also, in the section of letters about last week's column on box office numbers, Bialik discusses the fact that movie studios are always touting box office receipts in dollars unadjusted for inflation, instead of using inflation-adjusted numbers or ticket sales:

Studios don't have much incentive to make the inflation adjustments, because they'll make the numbers smaller. The entertainment press, however, could make this change pretty easily, as inflation numbers are readily available online. But they'd have to be prepared to give up many of the headlines touting new box-office "records."

However, such "records" are often as meaningless as the gas price "records" that are broken every few months. Moreover, box office receipts are at best a measure of the popularity of a movie, and not of its artistic or entertainment value. That the studios are always publicizing how much money they're making is a bandwagon appeal, aimed at getting us all to run like a bunch of lemmings to see the latest blockbuster.

Source: Carl Bialik, "Watching the Pollsters", The Numbers Guy, 6/1/2006

June 1st, 2006 (Permalink)

What's New?

The NEW AND IMPROVED Fallacy Files! The whole website is currently under reconstruction. I have revised the underlying HTML code, which will be invisible to you but should make the site work better. In the process, I have made some improvements to the layout and appearance of the site, and even rewritten some pages. In particular, the Taxonomy has been redesigned and its instructions rewritten, and the Sources & Resources page has some additions.

The current version of the site is just the basics, namely, all of the fallacies, the most important supporting pages from the main menu, together with this weblog. The remaining pages will be revised and uploaded over the next few months, including the archive pages for the weblog.

Please forgive any bugs, such as broken links, missing images, etc. Given that the revision is so extensive, including every page of the site, there are bound to be some problems which will need to be corrected. I will be fixing any bugs that I find as quickly as possible. Please assist me in this process by reporting any bugs to me.

Solution to the Ice Cream Diet Puzzle: The word "calorie" is ambiguous:

Therefore, a gram of ice cream actually supplies nearly 9,000 calories, so that the 27 calories needed to raise its temperature up to body heat is only a tiny fraction of the calories it supplies. The ice cream diet sounds good but it doesn't work. Sorry!

Source: "Pizza and Ice Water Diet", Professor Tangent

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