A lot of good arguments are spoiled by some fool who knows what he is talking about.

The line is a sardonic jab at the way “good arguments” can be undermined by the very presence of someone who is technically competent. It suggests that persuasive debate is not always governed by truth or expertise: a person who “knows what he is talking about” may complicate, qualify, or puncture a rhetorically effective case, thereby “spoiling” it for those who prefer neat, winning narratives. The humor depends on reversing expectations—calling the knowledgeable person a “fool”—to expose how audiences sometimes reward confidence and simplicity over accuracy, and how intellectual honesty can be inconvenient in polemical settings.