Commentary: Raising the Bar - Spotting the fallacious argument

Daily Record, The (Baltimore), Aug 29, 2003 by Special to The Daily Record

The fallacy of division is the mirror image of the fallacy of composition: It assumes that what is true of the whole is true of the collective parts. Just as it is erroneous to assume that players of average talent will be an average team, so also is it erroneous to infer the reverse - that an excellent team must consist of excellent players. What is true of a class may not be true of individual members of a class.

Non sequitur

The term non sequitur means it does not follow and refers to a claim that does not logically follow from the stated premises. In one sense, all logical fallacies are non sequiturs, but the label is ordinarily used in only three situations, all of which involve an erroneous or missing link.

The first is an argument that involves a completely illogical leap or assumes a false premise: The witness should not be believed because he smokes cigars. This argument assumes that all persons who smoke cigars cannot be believed. There is no logical connection between smoking cigars and credibility; therefore, the argument is a non sequitur.

The second occurs when there is a missing premise: People who wear nose rings are disgusting. There ought to be a law against wearing nose rings in public. The gap in this reasoning is the absence of the premise There ought to be a law against anything I find disgusting.

The third involves irrelevant reasons used to support a claim: I should get a salary increase this year because I received a raise last year. A person's performance and value to the employer justify a salary hike, not whether a raise was previously received. The argument avoids being a non sequitur if it contains additional information such as, My performance this year was better than last year.

Be on guard

Fallacies such as these are the product of careless advocacy and should be identified whenever they arise in litigation. Being prepared to spot fallacies in your opponents' arguments requires diligence and a solid understanding of logic, two assets strong lawyers demonstrate in their practice.

Trial lawyer and author Paul Mark Sandler is a partner with Shapiro Sher Guinot & Sandler in Baltimore. His column appears Fridays in The Daily Record.