The document discusses logical fallacies, which are mistakes in reasoning that make an argument invalid. There are two major groups of logical fallacies: fallacies of relevance and fallacies of insufficient evidence. Fallacies of relevance occur when the premises of an argument are irrelevant to the conclusion. Some examples of fallacies of relevance include personal attacks, attacking an argument's motive rather than its merit, ignoring one's own failures, and distorting or ignoring parts of an opponent's argument.