Module 5

Weak arguments and fallacies: spotting them in others, avoiding them in yourself

Every lawyer meets bad arguments: in the other side’s brief, in a judge’s question, in a client’s reasoning and, if honest, in their own first drafts. Recognising them is a skill, and it has two uses. The first is defensive: you can see what is wrong with an argument before it persuades someone, and you can say so precisely. The second is constructive: you can see the weak moves in your own writing and remove them before the other side does. This module introduces the common fallacies, which are patterns of reasoning that look convincing but do not support their conclusion, in the plain terms that lawyers use. It stresses a point that many lists of fallacies leave out: nearly every fallacy has a legitimate cousin. Attacking a witness’s credibility, citing an expert, warning of consequences and appealing to the human effect of a decision are all proper in the right circumstances. The skill is to tell the sound version from the weak one. The module also covers weaknesses that are particular to legal writing, and how to answer a weak argument effectively without name-calling. All the examples are invented.

General education on legal reasoning and argument, using invented cases, by-laws and people. It states common principles and does not describe any one country’s law, rules of evidence or professional conduct rules, which differ and change. It is not legal advice, and it does not replace the instruction of a law school or a supervising lawyer.