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July 28th, 2010 (Permalink)

Reader Response

Relating to our recent theme of the problem of expert opinion, a pseudonymous reader writes concerning the fallacy of argumentum ad verecundiam, which I call "the fallacy of misleading (or questionable) authority" rather than simply "appeal to authority", as it has been traditionally translated. The reader begins:

I take issue with qualifying the authority as "misleading" or "questionable." Regardless of the authority's credibility, a conclusion is never necessarily true because the authority has concluded it.

An example came up recently in which my opponent claimed that the Supreme Court is an authoritative interpreter of the constitutionality of a law, and therefore, if the Supreme Court concludes that the law follows (or not) the spirit of the Constitution, then the law factually follows (or not) the spirit of the Constitution. In response to this, I pointed out the famous Slaughter-house ruling in which the Supreme Court is likely to have incorrectly interpreted the law's Constitutionality. This alleged blunder is acknowledged by most legal scholars today. While my appeal to "most legal scholars today" is in effect the same fallacy, it still demonstrates the point that this informal fallacy says nothing about whether the authority factually is or is not correct. The only thing we can derive from an authority's conclusion is that the authority has concluded it. We cannot ever say that our conclusion is correct "because an authority says so." That's the point of this and all other fallacies.

Should we qualify ad populum as well? "Appeal to the misleading majority"? That's just silly. Just as the majority may or may not be correct when invoking that fallacy, so too the authority may or may not be correct when invoking this fallacy.

It's true that an expert opinion is not necessarily correct, but that just means an argument that appeals to it is invalid. I wouldn't consider an inductively strong type of argument to be fallacious, rather it would have to be uncogent to count as a fallacy. Cogent appeals to expert opinion are those that, while not necessarily true, are probably true, or are at least more likely to be true than an inexpert opinion. If the supposed "experts" in a given area are no more likely to be correct in their judgments than non-experts, then there are no experts in that area, in my opinion.

This is why it is a good idea to qualify "authority" in "appeal to authority" with some such qualifier as "misleading" or "questionable", lest people conclude―as you may have―that all appeals to expert opinion are logically fallacious. If that were true, then there would be no more reason to go to a medical doctor to have your illness diagnosed than to go to a medicine man, a witch doctor, or Joe the Plumber.

There's a legal saying that "hard cases make bad law", and the Supreme Court example is a "hard case". It opens up a distracting side issue, since your friend may have in mind the idea that the law is whatever the Court says it is, because the Court has the final say. Even if your friend is right, this is a feature peculiar to the structure of American law. For instance, I doubt anyone would think that if a medical doctor says you have cancer, you thereby have cancer, and the physician couldn't possibly be wrong. At best, the Supreme Court is a lone exception to the rule that experts are fallible, and it would be a mistake to generalize from this example since it is unrepresentative of the nature of expertise.

Ad populum is a different matter entirely, and I agree with you that it shouldn't be qualified in a way similar to ad verecundiam. However, this is because there's generally no good reason to think that the majority is more likely to be right than some minority―for example, the minority of experts! There may be some special situations in which a majority is more likely to be right than a minority, but in those cases the bandwagon appeal will not be fallacious. Otherwise, ad populum is almost always misleading, and we needn't qualify it.

July 26th, 2010 (Permalink)

What's New?

I've added a new entry to the Familiar Contextomies page.

Source: Familiar Contextomies: Thomas Jefferson, Fallacy Watch.

July 18th, 2010 (Permalink)

New Book: Wrong

The latest eSkeptic reviews the new book Wrong: Why Experts Keep Failing Us―And How to Know When Not to Trust Them by David Freedman. According to the review―and also its subtitle―Wrong focuses on how and why experts make mistakes. A couple of months ago, you may recall, I discussed this issue at some length (see the Resource, below) with respect to another new book, Massimo Pigliucci's Nonsense on Stilts. From the review, we learn that:

Most of the expert errors documented here…are not intentional, but originate in the cognitive biases to which everyone is prone. Like the rest of us, experts have sharper eyes for data that supports their hypotheses….

In other words, experts suffer from confirmation bias.

I'm unclear about what the author of the review is getting at in its last few paragraphs, unless the book has led him into a generalized skepticism about knowledge. The discovery that experts are fallible might cause a feeling of disillusionment in anyone who had trusted them blindly, but that's an equal and opposite over-reaction. As the reviewer mentions earlier, any such general skepticism will undermine itself:

Freedman knows his task leaves him open to the charge of begging the question: the same lack of certainty he says accompanies expert judgments must also apply to his own assumptions that particular expert claims are wrong. I agree with his defense that, though any individual claim may be mistaken, accumulating and pooling evidence allows us to converge on the truth.

While the reviewer thankfully doesn't abuse the phrase "begging the question" in the usual "raises the question" sense, what he's describing isn't really a circular argument. Rather, he seems to mean a vicious circle in a different sense, namely, a claim that undercuts itself. For instance, the statement "all statements are false" implies its own falsehood. In a similar though less obvious way, a general skepticism about expertise would be hoist on its own petard.

Here's a question that should be kept in mind while thinking about this book: is David Freedman himself an expert? Does he claim to be an expert? If so, what is he an expert in? If not, why should we read his book?

This looks like a potential book club book.

Source: David H. Voelker, "How Much Does Being Right Matter?", eSkeptic, 7/14/2010

Resource: New Book, Too, 5/12/2010

July 15th, 2010 (Permalink)

The Fourth Puzzle of the Unmatched Socks

Mr. Brown moved into the office shared by Mr. White, Mr. Black, and Mr. Grey. On Formal Friday, all four men wore ties to work. Each of the four wore a tie, socks, and shoes of colors that matched one of their names―that is, the articles of apparel were of the four colors white, black, grey and brown―but none of them wore anything that matched his own name. There was one white tie, one black tie, one grey tie, and one brown tie among them; similarly for the socks and shoes. Also, each man wore ties, socks, and shoes of three different colors (each pair of socks was one color; also, the shoes matched each other in color). Mr. Brown wore the white tie, while neither Brown nor Mr. White wore the grey shoes. What color tie, socks, and shoes was each man wearing?


July 10th, 2010 (Permalink)

What Darwin Got Right

I discussed Jerry Fodor and Massimo Piattelli-Palmarini (F&P)'s new book What Darwin Got Wrong at some length a few of months ago (see the Resources, below). Now, the London Review of Books has published a review by Peter Godfrey-Smith, and the latest eSkeptic has one by Donald Prothero. Check 'em out.

I haven't quite finished F&P's book, having gotten bogged down in the first half of it. However, as some reviewers have pointed out, the connection between the first half of the book and the argument of the second half is tenuous. In the first part of the book, F&P give examples of mechanisms other than natural selection that play a role in evolution. However, in the second, they seem to be arguing that natural selection plays little or no role in evolution―or, at least, little or no role in evolutionary explanations of the traits of organisms―and this is because of the supposed "intensional fallacy". Now, logically, the first part could be completely true and the second part totally false. As Prothero points out:

F&P review many of the recent developments in evolutionary biology, from neutralism to group selection to self-organizing systems to jumping genes to evo-devo. These important scientific discoveries have certainly broadened our understanding of how evolution works, but none of the people who made these discoveries doubt that natural selection still plays an important role in the process of evolution.

So, even though I haven't quite finished the book, there's one last point that I want to make about the "intensional fallacy" argument that I haven't made previously. While most of my previous criticisms have been made independently by others, such as Godfrey-Smith, I haven't noticed anyone make this one. Of course, that may be because it's wrong, but it still seems important to me and, therefore, worth getting on the record.

As background, here's Godfrey-Smith's description of "the intensional fallacy":

…[S]uppose we have a population of organisms and a new trait, T, appears in it. Individuals with T are more likely to survive to reproductive age, so on average they have more offspring. As T tends to be inherited, over time it increases in frequency in the population. It seems natural to say that there was selection for T. But what if there is another trait, T*, that organisms with T tend also to have? This might be because the genes that produce T also produce T*, or because the genes that produce T are close to those that produce T* in the genome and tend to be passed on together, or for other reasons. However the correlation arises, when explaining the increase in what we are calling ‘organisms with T’, we have to say why it is T that selection was favouring. Take the extreme case in which all organisms with T also have T*, and all with T* have T. Then it seems that natural selection is blind to the difference between them. So, Fodor and Piattelli-Palmarini say, whenever there is this kind of correlation between traits (it is ubiquitous, in various degrees), an explanation of the form ‘the population is now the way it is because trait T was favoured by natural selection’ is undermined.

They cast their argument within a framework derived from logic and the philosophy of language. There, two terms are said to be ‘co-extensive’ when they pick out exactly the same object or set of objects. Suppose that every animal that has a heart also has blood, and vice versa. Then the descriptions ‘animal with a heart’ and ‘animal with blood’ are co-extensive. Extending this usage, Fodor and Piattelli-Palmarini argue that two properties are co-extensive if all the same objects have those properties. So properties T and T* are co-extensive if everything with T also has T*, and everything with T* also has T. …

‘Intensionality’ is another term of art required here. A sentence is intensional if it can be changed from true to false, or from false to true, by substituting one co-extensive term in it for another. It might be true that ‘Bob thinks the morning star is bright’ but false that ‘Bob thinks the evening star is bright’ even though ‘morning star’ and ‘evening star’ refer to the same object. Sentences containing ‘thinks that …’ are often intensional. Fodor and Piattelli-Palmarini claim that an ‘intensional process’ is one that ‘distinguishes’ between co-extensive properties, and that Darwinism requires natural selection to be an intensional process, where in fact it is not. Darwinism is thus guilty of an ‘intensional fallacy’.

First of all, this is not a "logical fallacy" in the usual sense. It is a supposed "fallacy" in the sense of a mistake, and it is "logical" in the sense that it requires some logical concepts to explain. But it's not a logical mistake in an argument. There is a "logical fallacy" in the usual sense that may be called "the intensional fallacy", namely, the mistake of substituting co-extensional terms within an intensional context. But this ain't that.

Secondly, the point that I want to make is that properties can be co-extensive in different ways: for instance, the properties of being a unicorn and of being a flying pig are co-extensive, because both are empty. Yet, there could have been unicorns or flying pigs, in which case these classes would not have been co-extensive. In other words, there's no connection between the concepts of unicorn and flying pig that make them co-extensive, rather it just so happens that there is nothing corresponding to either concept.

In contrast, some properties are co-extensive because they are connected in some way: for example, the properties of being a unicorn and being a one-horned horse-like animal. Some properties, such as these, are connected definitionally and are, therefore, necessarily co-extensive; other properties are logically connected and, thus, also necessarily co-extensive.

In between those concepts that are contingently co-extensive and those that are co-extensive by logical necessity are a range of others which are connected, but whose connections are weaker than logical necessity. Some properties are causally connected in such a way that they will be co-extensive in any physically possible world, though there may be logically-consistent worlds with different physical laws in which the properties are not co-extensive.

The strength of the connection between co-extensive properties is relevant to the question of which properties are "invisible" to natural selection. At one end of the range, properties that are definitionally or logically co-extensive will certainly be "invisible". At the other end, properties which are only accidentally co-extensive should not be "invisible", since it will be possible to imagine an experiment to show to what degree each property contributes to the survival of an organism that has it.

To borrow an example from Godfrey-Smith, suppose that the two color traits T and T* are co-extensive, where T is an exterior color and T* an internal color. Also, assume that this co-extensiveness is just a coincidence, that is, there is no connection of any sort between the two traits (this differs from Godfrey-Smith's version of the example). Is it possible to say that T was selected for but T* was not? Of course! We can experimentally change T and see what happens: if T acts as camouflage, then changing it will adversely affect the organism's survival; in contrast, experimentally changing T* may have no effect on survival at all. If that is the case, then T was selected for and T* was not.

So, F&P are wrong to claim that all co-extensive properties are "invisible" to natural selection, though those that are necessarily connected are. Is this a problem for the theory of natural selection? I don't think so. It does mean that natural selection cannot make such fine distinctions as artificial selection, but what of it?



July 2nd, 2010 (Permalink)

The Best Contextomy So Far!

Can a critic pan a movie so badly that it's impossible for a clever ad writer to use a blurb from it to sell the movie? An ad for the new "Twilight Saga" movie Eclipse uses the following quote:


Of course, the best so far might be awful if the previous movies were even worse. Sure enough, the quote appears to be taken from an article called "a hater's guide" to the movie. Here's some of the missing context:

Eclipse is the best Twilight movie so far. But it may also be the third worst vampire movie of all-time.

I can't help but admire the brazenness of that!


Resource: Christopher Beam, "[Best] Film Ever!!!", Slate, 11/25/2009. Explains the main tricks of the movie blurbing trade.

Solution to the Fourth Puzzle of the Unmatched Socks:

Tie Socks Shoes
Mr. Black:BrownWhiteGrey
Mr. Grey:BlackBrownWhite
Mr. Brown:WhiteGreyBlack
Mr. White:GreyBlackBrown

Since neither Mr. Brown nor Mr. White wore the grey shoes, Mr. Black must have worn them (Mr. Grey couldn't do so because they would match his name). Since Mr. Brown wore the white tie, Mr. Black must have worn the brown one (he couldn't wear the black one because it would match his name, nor the grey one because it would match his shoes, so brown is the only color left). Therefore, Mr. Black must have worn white socks, since he can't wear black ones (they would match his name), or grey ones (they would match his shoes), or brown ones (they would match his tie).

Mr. Grey wore the black tie, since Mr. Brown wore the white one, Mr. Black wore the brown one, and the grey one would match Mr. Grey's name. Also, Mr. Grey wore brown socks, since he couldn't wear the grey ones (they match his name), the white ones (Mr. Black is wearing them), or the black ones (they would match his tie). Therefore, he must be wearing the white shoes, since that's the only color left that doesn't match his name.

Mr. Brown must be wearing the black shoes, since grey and white are taken (by Mr. Black and Mr. Grey, respectively) and brown would match his name. His socks must be grey, since white is taken (by Mr. Black), black would match his shoes, and brown would match his name. So, white is the only color left for his tie that doesn't match his name.

The only remaining colors for Mr. White are a grey tie, black socks, with brown shoes. I didn't say that these guys had any fashion sense!

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