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Chapter 10. My Way or the Highway: Speak... > Appealing to Logic - Pg. 76

My Way or the Highway: Speaking to Persuade 76 Logical arguments rely on objective facts instead of personal opinions or preferences. In turn, each logical argument in your speech must be supported by evidence: facts, statistics, expert testimony, or details about the argument. The basic organization for a persuasive speech developed on logical arguments looks like this: Introduction:Catches the listener's attention and states your argument Body:States each logical argument and presents supporting evidence Conclusion:Restates your argument and summarizes your main points Logical arguments are developed in two basic ways: by inductive reasoning and by deductive rea- soning. Inductive Reasoning Inductive reasoning is thinking from parts to the whole by drawing conclusions from specific facts. Scientists use inductive reasoning when they state a hypothesis and then conduct tests to see whether it's valid. If repeated experiments produce the postulated result, the scientists are able to conclude that their hypothesis is likely valid. For inductive reasoning to be solid, there cannot be any exceptions to the conclusions you draw. For example, if you saw three white cats and concluded that all cats are white, your conclusions would not be valid. Deductive Reasoning Deductive reasoning is thinking from the whole to the parts. Start with a general statement and then proceed to specific facts that follow from the statement. Sometimes the deductive argument at the center of a persuasive speech can be stated in three sentences, as in this example: Major premise:All chocolate is fattening. Minor premise:This candy bar is chocolate. Conclusion:Therefore, this candy bar is fattening. To use deductive reasoning correctly, you must first make sure that the major premise is true (this is often accomplished by using inductive reasoning). If your major premise is not valid, the rest of the argument will collapse. After you have your major premise down, craft a minor premise that logically follows it. Then decide if the conclusion is sound. Finally, make sure that any qualifications of your first statement are repeated in the conclusion. However, a speaker rarely lays out a deductive argument this neatly. In most cases, for example, the first statement will be implied rather than stated. Use the following check list when writing a persuasive speech using logical appeals: · · · · · · · · Is my topic appropriate to my audience? Have I sufficiently narrowed my topic? Did I research how other people feel about this topic? Did I select my side of the issue? Did I make my opinion as my thesis? Did I select the most effective facts? Did I weigh both inductive and deductive arguments? Did I check my inductive and deductive arguments to make sure that they're valid?