A taste of logic! Arguments: a form of or informal mode of reasoning using premises and conclusions. Premises: the whys; Conclusions: the what

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1 A taste of logic! Logic vs Rhetoric: Logic persuades on the basis of reasons that hold for anyone or all people. Rhetoric persuades on the basis of force and personal appeal. Arguments: a form of or informal mode of reasoning using premises and conclusions Premises: the whys; Conclusions: the what 2 types: Deductive and Inductive arguments Deductive: All men are mortal Socrates is a man

2 Principle of non-contradiction!! All logics based on this! A A Contradiction. A cannot be true or false at the same time, under the same conditions of time.! eg. Dogs are friendly vs Dogs are not friendly. As contradictions one must be true and the other false.! Not (P and not-p)

3 More on deduction and induction!! Deductive Arguments: validity and invalidity: guaranteeing the conclusion! A valid argument: If the premises are true, then the conclusion is necessarily true.! Soundness: Truth of premises and validity of structure! Common Patterns: Disjunctive, Hypothetical! Disjunctive: It was either Phyllis or Fred. It wasn t Phyllis. Therefore it was Fred. pp ! Hypothetical (Conditional)! Categorical

4 Inductive arguments!! Conclusion always goes beyond, states more than the premises allow.! Conclusions admit of degrees of probability and are never guaranteed. If premises are true, conclusion is likely or should be so in a good inductive argument.! Conclusion is like a hypothesis.! Always possible that new evidence or some reason could refute the hypothesis. Or, that a different conclusion could follow.! Every A we have observed is a B! Therefore, A is a B: Eg. Every Crow we have observed is black, hence?

5 Induction continued!! Other common patterns:! Prediction of a future event based on past ones or current knowledge.! Generalization: Eg. The driver of every Italian bus we rode had a beard. Therefore, all Italian bus drivers have beards.! Hasty Generalization (a fallacy).! Sherlock Holmes: from evidence to indictment; the process of elimination.

6 Induction:probability!! Degrees of Probability: Even the highest cannot guarantee that the conclusion follows! Logical Possibility: Supplying counter-examples for a philosophical claim that is Universal! Refutation: In Theory choice: Against confirmation! Imagining these possibilities or examples: Multiplying the options--creative thinking

7 Creative Thinking!! Example: The People s Choice Awards determine who are the best artists. American Idol as example! Angles, perspectives!!! Fallacious, appeals to the majority to determine what is the best. Based on how well the artist sells!! The need for interpretation. Vital in reading philosophy! How about using definition? We could define the best

8 Creative thinking!! What is the problem? First step, no longer thinking about the problem as a problem, but an opportunity for insight and advancement and Inspiration!! Back to example. Can we save the claim?! The nature of fallacies: common and recurring errors in thinking. (See book for list)! What if the people who all vote or choose are correct? What makes them correct? Authority, knowledge, expertise?

9 other critical tools!! Alternate Conclusions: remember nature of arguments! Look to see whether other conclusions more readily follow from premises! Immanent Critique: look for weak premises in argument! Search for Meaning: In the early going we are concerned about how well you understand the concepts of metaphysics.! What do these concepts mean? What do they tell us about the nature of reality? Are they clear, confused, used inconsistently?

10 other critical tools Refutation: Socratic elenchus The whole not the parts, please and thanks, getting ripped off Inadequate justification Vague concepts: define one s terms Some rules of definition: narrowness, broadness, circularity, negative

11 other critical tools Tautologies: ex. A bachelor is an unmarried man A pejorative term used to deride a claim because it purports to be informative but in fact simply repeats the meaning of something already understood. i.e. A criminal has broken the law. I.e. P or not P