Courses in symbolic logic (usually titled "Logic I & II" - propositional logic and predicate logic ) are good for mathematical thinking. But usually the instructor will also take time to go through the common fallacies of argumentation [Edit: See "fallacies" in Google]. Often this is the only explicit exposure to coherent argumentation that a student gets in his college career.

Had I to do it over again I would have started by studying rhetoric (the art of persuasion), a larger field of study that seems (to me) more relevant.