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Unformatted text preview: Branden Fitelson Philosophy 12A Notes 1 Announcements & Such Three videos from Animusic 2 Administrative Stuff HW #2 resubmisions due Friday (4pm, drop box). Please attach your original assignment to your resub! See my HW Tips & Guidelines Handout. Make sure you have problem #12 from p. 33 of the 4 th edition. Its about the Mayors election (and the council members). I have posted two handouts: (1) solutions to problems from lecture on logical truth, equivalence, etc., and (2) three examples of the short truth-table method for validity (to be discussed soon). HW #3 has been posted. Its on truth-table methods for validity. Next: Chapter 3, Continued LSL Semantics Truth-table methods for LSL validity. UCB Philosophy Chapter 3 09/26/08 Branden Fitelson Philosophy 12A Notes 2 The Exhaustive Truth-Table Method for Testing Validity Remember, an argument is valid if it is impossible for its premises to be true while its conclusion is false. Let p 1 , . . . , p n be the premises of a LSL argument, and let q be the conclusion of the argument. Then, we have: p 1 . . . p n q is valid if and only if there is no row in the simultaneous truth-table of p 1 , . . . , p n , and q which looks like the following: atoms premises conclusion p 1 p n q We will use simultaneous truth-tables to prove validities and invalidities. For example, consider the following valid argument: UCB Philosophy Chapter 3 09/26/08 Branden Fitelson Philosophy 12A Notes 3 A A B B atoms premises conclusion A B A A B B VALID there is no row in which A and A B are both , but B is . In general, well use the following procedure for evaluating arguments: 1. Translate and symbolize the the argument (if given in English). 2. Write out the symbolized argument (as above). 3. Draw a simultaneous truth-table for the symbolized argument, outlining the columns representing the premises and conclusion. 4. Is there a row of the table in which all premises are but the conclusion is ? If so, the argument is invalid; if not, its valid. We will practice this on examples. But, first, a short-cut method. UCB Philosophy Chapter 3 09/26/08 Branden Fitelson Philosophy 12A Notes 4 The Short Truth Table Method for Validity Testing I Consider the following LSL argument: A (B & E) D (A F ) E D B This argument has 3 premises and contains 5 atomic sentences....
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This note was uploaded on 09/23/2009 for the course PHIL 12A taught by Professor Fitelson during the Spring '08 term at University of California, Berkeley.
- Spring '08