Wilson, Douglas, and Nathan D. Wilson. The Rhetoric Companion: A Student's Guide to Power in Persuasion. Moscow, Idaho: Canon, 2011.
Lesson 11, “The Basics of Reasoning” pp. 59-62.
In this lesson Wilson discusses the importance of sound reasoning in arguments. He introduces three important laws of reasoning. “These three laws may be summed up by saying there is no third way [between true and not true], truth is truth, and truth excludes falsity” (Wilson 2011, 59). To be assured of a sound argument it is also important to define a “statement.” “A statement is a sentence which can be said to be either true or false without contradiction” (Wilson 2011, 59). Not all sentences are statements. The statement is very precise. It may serve as a premise or a conclusion, and in a lengthy argument it may serve as a conclusion of one point and a premise of another. Failure to use sound reasoning is called a “fallacy” and may be either a failure of structure (form) or may involve ignoring or distracting from the argument. Wilson also distinguishes between deductive and inductive arguments (Wilson 2011, 60). The deductive moves from general to specific and is either valid or invalid. The inductive moves from specific to general and may be stronger or weaker.