Logical Appeals

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Logical Appeals

  1. 1. Logical Appeals
  2. 2. What logos is NOT… <ul><li>NOT citation of scientific facts and/or statistical evidence. </li></ul><ul><li>NOT Quotations of the “testimony” or “scholarship” of experts. </li></ul><ul><li>(This kind or argumentation comes under the heading “extrinsic proofs”) </li></ul>
  3. 3. Deductive Reasoning <ul><li>Moving from the universal / general to the </li></ul><ul><li>particular. </li></ul><ul><li>The Classic Syllogism: </li></ul><ul><li>Major premise: All men are mortal </li></ul><ul><li>Minor premise: Socrates is a man </li></ul><ul><li>Conclusion: Socrates is mortal </li></ul>
  4. 4. The Enthymeme <ul><li>A kind of informal deductive argument / syllogism </li></ul><ul><li>The premises may be probable truths or commonly held beliefs (not necessarily universally accepted). </li></ul><ul><li>The premises and/ or conclusions may be left unstated (implied) </li></ul><ul><li>There may be multiple premises needed to reach a conclusion. </li></ul>
  5. 5. Susan B. Anthony Enthymeme <ul><li>Major premise: The Constitution seeks to </li></ul><ul><li>“secure liberty” for all people who are </li></ul><ul><li>citizens of the United States. </li></ul><ul><li>Minor Premise: Voting is the key way </li></ul><ul><li>people exercise liberty. </li></ul><ul><li>Minor Premise : Women are persons. </li></ul><ul><li>Conclusion: Women should have the right </li></ul><ul><li>to vote. </li></ul>
  6. 6. Sample Enthymeme from “A More Perfect Union” <ul><li>Major Premise: You should not disown </li></ul><ul><li>your family just because you disagree </li></ul><ul><li>with them. </li></ul><ul><li>Minor Premise: Rev. Wright has been like </li></ul><ul><li>family to me. </li></ul><ul><li>Conclusion: I will not disown him. </li></ul>
  7. 7. Key Question for analyzing enthymematic proofs <ul><li>What (often unstated) premises would I have to accept in order to believe this argument? </li></ul><ul><li>Can I disprove the premises on which this argument rests? </li></ul><ul><li>Can I reach a different conclusion by starting from a different set of premises? </li></ul>
  8. 8. Inductive Reasoning <ul><li>Moves from particulars to the universal. </li></ul><ul><li>Proceeds by citing many different examples that all lead up to one broader conclusion. </li></ul>
  9. 9. Rhetorical Examples ( paradiegma ) <ul><li>Looser form of inductive reasoning (that doesn’t require reaching a universal conclusion) </li></ul><ul><li>A past action / event (real or imagined) that can be used to support an argument. </li></ul><ul><li>Often involves vivid description. </li></ul>
  10. 10. Analogy <ul><li>Placing one (often hypothetical) example </li></ul><ul><li>next to another for the purposes of </li></ul><ul><li>comparison. </li></ul>
  11. 11. Questions about Rhetorical Examples <ul><li>Is the example relevant to the issue under discussion? </li></ul><ul><li>Can a counterexample be found that proves the opposite case? </li></ul><ul><li>Is the audience familiar with this example and what kind of emotional reaction will they have to it? </li></ul>
  12. 12. Maxims <ul><li>Well-known sayings, quotes, or proverbs </li></ul><ul><li>that can support an argument. </li></ul><ul><li>Example: “All are created equal”; “an eye </li></ul><ul><li>for an eye”; “better late than never” </li></ul>
  13. 13. Signs <ul><li>Observable facts / realities in the world that can be taken as a “sign” that something is happening / will happen. </li></ul><ul><li>Example: Melting polar ice caps as “sign” </li></ul><ul><li>of global warming / climate chage </li></ul>

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