Critical Thinking: Analyzing and Evaluating ArgumentsKathleen Maloney Lanzhou University May 11, 2009Reminder: Authors: Greg Bassham, William Irvin, Henry Nardone, and James M. Wallace Title: Critical Thinking: A Students Introduction Location: Foreign language library, third floor of the main library.Outline of Lecture Series May 4th, 2009: Critical ThinkingAn introduction May 11th, 2009: Critical Thinking Analyzing and Evaluating Arguments May 18th, 2009: Critical ThinkingSkills for Reading and WritingOutline of Todays Lecture Part One: Deductive Arguments vs. Inductive Arguments Part Two: Logical Fallacies Part Three: Analyzing Arguments Part Four: Evaluating Arguments Part Five: Summary and ActivityPart One: Deduction and Induction Deductive vs. Inductive Arguments Deductive and Inductive Indicator Words The Principle of CharityDeductive vs. Inductive Arguments People often describe the difference between deductive arguments and inductive arguments in the following way: Deductive arguments move from general premises to particular conclusions. Inductive arguments move from particular premises to general conclusions. However, this is WRONG!Deductive Arguments Deductive arguments claim that if their premise is true then their conclusions must be true. A common pattern for deductive arguments is: All A is B. All B is C Therefore, all A is C.Inductive Arguments Inductive arguments simply try to show that if their premises are true, then their conclusions are probably true. A common inductive argument pattern is: Things like X tend to be Y. I expect a new X. It will probably be Y.Deductive vs. InductiveDeductive Arguments Claim ThatInductive Arguments Claim ThatIf the premises are true, then the conclusion must be true.If the premises are true, then the conclusion probably is true.It is impossible for all of the premises to be true and the conclusion false. It is unlikely that the premises are true and the conclusion is false.The truth of the premises guarantees the truth of the conclusion. The truth of the premises makes the conclusion likely This table is quoted from Bassham, Irwin, Jones, and Wallace, Critical Thinking, pages 55-56.Deduction Indicator Words Some common deduction indicator words are: Certainly Definitely Absolutely Conclusively It logically follows It is logical to conclude This entails that It must be the case thatThese indicator words are quoted from Bassham, Irwin, Jones, and Wallace, Critical Thinking, page 57. Induction Indicator Words Some common induction indicator words are: Probably Likely It is plausible to suppose One would expect thatThese indicator words are quoted from Bassham, Irwin, Jones, and Wallace, Critical Thinking, page 57. The Principle of Charity Inexperienced writers often treat their opponents with a high level of skepticism. This is a terrible habit to get into. Instead we should try to remember to always follow the Principle of Charity when dealing with someones opposing argument.The Principle of Charity “When interpreting an unclear argument or passage, always give the speaker or writer the benefit of the doubt. Never attribute to an arguer a weaker argument when the argument permits us to attribute to him or her a stronger one. And never interpret a passage as a bad argument when the evidence reasonably permits us to interpret it as not an argument at all” (59).The Principle of Charity “When interpreting an unclear argument or passage, always give the speaker or writer the benefit of the doubt.” “Never attribute to an arguer a weaker argument when the argument permits us to attribute to him or her a stronger one.” “And never interpret a passage as a bad argument when the evidence reasonably permits us to interpret it as not an argument at all.”The Principle of Charity Why use the Principle of Charity? When we are generous and respectful, we encourage others to act in the same way. When we use the Principle of Charity, we make our opponents argument as strong as it can be. We improve more from confronting challenging opponents than from attacking weak ones.Part Two: Logical Fallacies Fallacies of Relevance Common Fallacies of Relevance Fallacies of Insufficient Evidence Common Fallacies of Insufficient EvidenceFallacies of Relevance Remember from last week the importance of relevance (相关 ) in critical thinking. Fallacies (谬论) are false or mistaken ideas that often sound plausible but are in fact untrue or illogical. Thus, fallacies of relevance occur when people try to support an argument with irrelevant information.Common Fallacies of Relevance Personal Attack: instead of analyzing and evaluating the argument on its own merit, we attack the quality of the person making the argument. Attacking the Motive: instead of analyzing and evaluating the argument on its own merit, we claim that the person making the argument is doing so for selfish reasons.Common Fallacies of Relevance Two Wrongs Make a