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Notes on Logic:

Informal, Deductive, and Inductive

Posts tagged with "slippery slope"

<i>Tu Quoque</i> as <i>ad Hominem</i>

Saturday, 10. March 2007, 17:49:55

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The central purpose of "Notes on Logic" is to provide examples and brief analyses of logical argumentation. These analyses often call into question the exact nature of a fallacy. What is the difference between an argument and a persuasive appeal? Are persuasive appeals only fallacies when they adduce logical arguments?

I'm assuming that a fallacy can occur only in the context of an argument--not the kind of arguments involving emotional disagreements, but the kind of argument where a conclusion is claimed to logically follow from reasons or evidence presented.

Let's take a look at two passages from Time magazine's "Letters to the Editor" illustrating the tu quoque. In both examples, the issues in the original argument are dropped, and the character of the author of the argument is addressed, instead. Since the contextual evidence indicates the two replies are intended to oppose the original arguments, the tu quoque's cited here may be considered fallacious appeals.

Even though the tu quoque is an informal fallacy (a fallacy variant of ad hominem), its structure is most often like this, as described in Wikipedia:

A makes criticism P.
A is also guilty of P.
Therefore, P is dismissed.


When presented in this manner, the argument structure reveals the irrelevancy clearly. Another variant of the tu quoque is discussed by Julian Baggini, the editor of The Philosophers' Magazine, in "Bad Moves: Tu quoque."

The first passage is on the subject of horsemeat as a part of the diet of many countries.

Would You Dine Equine?
[Joel Stein] said that in the U.S. we oppose eating horsemeat because we think "like a 14-year-old girl." He sounds like an 8-year-old boy who pulls the wings off flies for fun. Perhaps Stein should also order some cat, dog and hamster meat.
Karla LaFitte
Spring, Texas


(Karla LaFitte, "Would You Dine Equine?" in "Letters," Time, 169 No. 10 (5 March 2007), 15.)

Notice how not only is there a tu quoque present, but also there is a parting hint of the slippery slope fallacy.

The second passage is related to a news story about NASA astronaut Lisa Marie Nowak:

A Woman Scorned
Jeffrey Kluger stated that "In the tut-tut world of exposé journalism, astronauts—particularly women—misbehave at their peril." I'm not sure exactly how women these days are "misbehaving," but I am sure that there are countless successful, powerful women who would be incensed by your characterization. Just take a look at the way our male politicians are acting and tell me that they are not the ones misbehaving at their peril.
Katie McGuire
Danville, Calif


(Katie McGuire, "A Woman Scorned" in "Letters," Time, 169 No. 10 (5 March 2007), 15.)

Again, this passage fits closely the formal structure described above for the tu quoque fallacy. Also, there's a suggestion of another compounding fallacy. The snob appeal of an ad populum purportedly adds support to Katie McGuire's conclusion by pointing out that "countless successful, powerful women who would be incensed by [the] characterization."

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More on Non-Fallacies

Wednesday, 28. June 2006, 01:14:02

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As noted, in an argument, a conclusion is claimed to logically follow from the truth of other statements, termed "premises." Hence, an argument consists of a minimum of two statements. Consequently, a statement, by itself, does not constitute an argument. Moreover, a series of statements by themselves, without a claimed logical connection, should not be considered an argument.

When a captious critic does not adhere to the principle of charity, it's common to impute fallacious reasoning to an author. For example, consider the following compound statement:

The disappearance of punctuation ... indicates an enormous shift in our attitude to the written word, and nobody knows where it will end.

(Lynn Truss, Eats, Shoots & Leaves (New York: Gotham Books, 2004), xxvi.)

A critic might easily attribute the fallacy of Slippery Slope to this passage.

The Slippery Slope fallacy is succinctly defined in the Wikipedia as

... an argument for the likelihood of one event or trend given another. Invoking the "slippery slope" means arguing that one action will initiate a chain of events that will lead to a (generally undesirable) event later.

"Slippery Slope," Wikipedia (June 27, 2006) URL=<http://en.wikipedia.org/wiki/Slippery_slope>

The fallacy occurs if there is no necessary connection in the series of events leading to the feared final event.

So, the critic might reconstruct Lynne Truss's argument as follows:

(1) Correct punctuation is disappearing.
(2) The disappearance of correct punctuation indicates a shift in attitudes.
(3) This shift in attitudes results in widespread carelessness among people.
(4) Widespread careless leads to disastrous results for all concerned.

The argument that (1) leads to (2) and, in turn, to (3) and finally (4) would be an instance of the Slippery Slope fallacy. However, this argument was not intended by Truss's compound statement.

Her statement is best taken as two observations, exaggerated for rhetorical effect:

(1) The disappearance of punctuation ... indicates an enormous shift in our attitude to the written word.
(2) Nobody knows where it (i.e., the shift) will end.

The word "and" connects clauses of equal status. If she had thought the latter statement followed from the first, then the latter statement would be preceded by a conclusion indicator such as "thus," "hence," or "therefore."

Often, persons trained in logic and critical reasoning mistakenly attribute errors in reasoning to persons who pique interest when writing with emotive significance.

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