Speech

Chapter 10: Logic and Reasoning

Overview

Evidence is anything that establishes a fact or gives us reasons to believe something. To be an effective speaker, you must give your audience reasons to believe what you are saying. By using reasoning and logic, supported by evidence, you will become a successful communicator. There are several types of reasoning, including inductive reasoning, reasoning by sign, reasoning by analogy, and deductive reasoning. Inductive reasoning moves from specific instances to a generalization. Reasoning by sign is a type of inductive reasoning that is based on physical evidence. Reasoning by analogy is another type of inductive reasoning that is based on similarities between a familiar object or event and an unfamiliar object or event. Deductive reasoning, unlike any type of inductive reasoning, moves from generalizations, or premises, to a specific instance.

In order to build a speech based on solid logic and reasoning, it is important to learn to recognize and avoid fallacies. Fallacies are errors in reasoning or mistaken beliefs. Some of the more common fallacies are hasty generalizations, false premises, circumstantial evidence, mistaken causality, playing with numbers, false analogy, ignoring the question, and begging the question. Regardless of what your audience wants to hear, present accurate information and stay true to your convictions.