Fallacies

About this course

Seven units cover seven fallacies: straw man, ad hominem, hasty generalization, slippery slope, false dilemma, circular reasoning and the appeal to authority. Each unit explains how the move works, when a similar argument is fair, and how to reply. That middle part matters. Not every remark about a person is a fallacy: when a claim rests on someone's word alone, such as a witness who says they saw an accident, evidence that the witness has lied before or could not see the road is relevant.

The units use short made-up examples, and the course states that all ads, headlines and conversations are invented for teaching and quote no real company, newspaper, politician or person. For the straw man, the fix is to restate the other person's view in a form they would accept before you reply. When A says homework should be shorter on weekends and B answers that abolishing all homework would make students forget everything, B has refuted something A never said. For hasty generalization, two cousins who studied abroad and got good jobs do not show that studying abroad guarantees one. The slippery slope follows the Stanford Encyclopedia of Philosophy's description of an argument that goes from a starting point through small steps to an undesirable conclusion and then rejects the starting point. For the false dilemma, the simplest reply is a question: are those really the only two choices?

Circular reasoning gets a diagram in which the premise is offered for the conclusion but is believed only because of it, so nothing outside the loop holds it up. The appeal to authority separates reasonable reliance, such as a relevant expert body giving a forecast in its own field, from authority used outside its field, like celebrity endorsements.