Logical Fallacies, Part 11: Tu Quoque

The tu quoque fallacy (Latin for “you too”) is a close relative of the ad hominem attack. (See the July 15, 2006 entry on this blog.) Tu quoque appears when deflecting attention from a criticism by asserting that the same criticism applies to the critic.

Deposed Iraqi leader Sadaam Hussein has tried the tu quoque argument by insisting that he should not be on trial for war crimes since the United States is guilty of war crimes. The problem with Hussein’s argument is that anyone else’s wrong does not make his crimes any less wrong.

Here’s a business example:

The Chief Financial Officer has said that the Research and Development group is over budget on Project X, but he is not bearing down as much on Accounting for overspending.

The writer’s complaint does nothing to justify Research and Development being over budget.


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Logical Fallacies, Part 10: Hasty Generalization

The hasty generalization occurs when stating a generalization with insufficient evidence. Example:

The company lost $11 million in the first half 2006; therefore, it will end the year just as poorly.

Perhaps the $11 million loss is an improvement over previous periods. Maybe the loss is a one-time or cyclical situation. It could be that the loss was from an investment which will soon become profitable. The evidence is just not there to make this claim.


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Logical Fallacies, Part 9: Guilt by Association

The guilt by association rhetorical flaw arises when the writer unreasonably associates an opponent or a proposition with a guilty party. It is related to the red herring (see the previous entry, August 26, 2006). Example:

How can we elect a man who served under an impeached president?

The thinking is flawed because of its assumption that anyone associated with the impeached president must be just like the impeached president.

Conversely, Check your endorsements as well. Equally misleading could be honor by association, in which the writer unreasonably associates an ally or a proposition with an esteemed party. Example:

The fact that the employee leave policy is supported by Governor Richford is sufficient reason to establish it.

Reasonable people expect more evidence than a governor’s endorsement to support a claim.


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Logical Fallacies, Part 8: Red Herring

When writers choose an unrelated point to distract readers from the real issue, they are committing the logical fallacy of a red herring . If you’ve ever heard or said, “You always disagree with me,” you’ve experienced a red herring. The term originates from the use of smoked herring to distract hunting dogs following a scent trail. Example:

Cicero Architectural & Engineering Consulting promises a profitable year. We have heard such claims before—from the likes of Fashion First Textiles and Medusa Boutiques—both of which yielded disappointing results in their first year after emerging from bankruptcy.

The textile and boutique businesses could not be more unrelated to an architectural and engineering firm. In addition, Cicero Consulting was not emerging from bankruptcy. By raising this irrelevant issue, the writer hopes to scores points in discrediting Cicero’s claim. Educated readers quickly detect this flaw.


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Logical Fallacies, Part 7: Non Sequitur

The non sequitur is closely related to the post hoc argument. The non sequitur (Latin for “it does not follow”) occurs when the writer incorrectly links two events or draws a conclusion that contradicts its premise. We also use the term non sequitur to refer to nonsensical statements in general. Example:

Sensation’s sales force needs to be more aggressive in territories the company recently entered. How ironic, then, that Sensation has enjoyed a six-year track record of uninterrupted growth.

In the framework of this sentence, past results have nothing to do with current plans in a new area of business. In fact, the company might have enjoyed six years of uninterrupted growth precisely because it takes aggressive positions in new territories.


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Logical Fallacies, Part 6: Post Hoc Reasoning

The term post hoc reasoning comes from the Latin phrase post hoc, ergo propter hoc (after this, therefore because of this). The writer incorrectly assumes that one event caused another just because the first event preceded the second event. Example:

The Firm lost $1.5 million in assets last fiscal year. Undeniably, management lost its resolve to stem operating losses after CEO Mitchell’s retirement.

Perhaps the CEO’s retirement did have an effect on the company’s losses; however, the absoluteness of the claim defies clear thinking.


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Logical Fallacies, Part 5: Equivocation

An equivocation is the use of different meanings of the same word to argue that the word means the same in each instance. Example:

We understand that runoff from Kennedy Park into the Raritan River is of great community concern; however, the runoff between the mayoral cadidates seems to generate little local interest.

Obviously, the environmental and political meanings of runoff are vastly different, so this comment would be met with skepticism or derision.


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