In terms of logic – part two

Last week, we discussed some basic logical terms often misused by lawyers. This is part two of that subject.

Fallacy can refer in many contexts to any mistaken conclusion or assumption, but when you are talking about arguments—as you probably will be if you use this term in a brief—you should use “fallacy” in its logical sense.

A fallacy is a flaw that renders an argument invalid—meaning that its conclusion does not follow from its premises (whether they are true or not). For example:

Premise 1: Jill assaulted Jack.

Premise 2: Punching someone is assault.

Conclusion: Jill punched Jack.

is a fallacious argument (because there are other ways to commit assault besides punching). It is a fallacy even if the premises and the conclusion are true, because the conclusion cannot be logically derived from the premises.

Non sequitur is another term for a logical fallacy. It can also be used to refer to a statement that doesn’t follow from what preceded it, regardless of the formal logical relationship of the two. Example: “Plaintiff was three hours late for his deposition. He is a German citizen.”

“Non sequitur” comes from Latin (for “it does not follow”), but has become sufficiently widespread in English that it should not be italicized.

A dilemma is a choice between two alternatives (as the prefix “di” suggests). You probably shouldn’t use it in your briefs to refer to a difficult decision among many alternatives, though this usage is certainly not uncommon.

A straw man is an inaccurate description of the other side’s position, formulated so that you can destroy it. The straw man position is much weaker than the true position, making the task of demolishing it much easier. Judges are unimpressed by straw man arguments, when they recognize them as such.

Perhaps the even greater danger of a straw man argument is that they may convince lawyers making them that the other side’s views are ridiculous and weak: when they must confront the real thing, they may be totally unprepared.

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