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Unformatted text preview: Branden Fitelson Philosophy 12A Notes 1 Overview of Todays Lecture Todays Music: Black Roots Richard will have extra office hours from 3:305 today. My office hours are 45:30 on Wednesdays. HW #2 due Friday @ 5pm in the 12A Drop Box (outside 301 Moses). Make sure you follow the guidelines/hints on my HW Tips Handout The mid-term is next Thursday (in class). Ill post a sample tomorrow. And, I will discuss the sample exam in lecture next Wednesday. I have posted a handout on the short method for testing LSL validity. I will be going over this handout in lecture very soon. More 12A Practice Problems can be found in: Schaums Outline of Logic Today: Chapter 3, Continued UCB Philosophy Chapter 3 (Contd) 06/02/10 Branden Fitelson Philosophy 12A Notes 2 Abstract Argument Logical Form LSL / LMPL / LFOL Symbolization Chapters 2, 5 & 7 English Argument Valid Form? Deciding Formal Validity Chapters 3 , 4, 6 & 8 Valid English Argument? Valid Abstract Argument? Articulation of Thought in English UCB Philosophy Chapter 3 (Contd) 06/02/10 Branden Fitelson Philosophy 12A Notes 3 p p p q p & q p q p q p q p q p q p q UCB Philosophy Chapter 3 (Contd) 06/02/10 Branden Fitelson Philosophy 12A Notes 4 Chapter 3 Semantics of LSL: Truth Functions VII If our truth-functional semantics for doesnt perfectly capture the English meaning of if . . . then . . . , then why do we define it this way? The answer has two parts. First, our semantics is truth-functional . This is an idealization it yields the simplest (Newtonian) semantics. And, there are only 2 4 = 16 possible binary truth-functions. Why? So, unless one of the other 15 binary truth-functions is closer to the English conditional than is, its the best we can do , truth-functionally . More importantly, there are certain logical properties that the conditional must have. It can be shown that our definition of is the only binary truth-function which satisfies all three of the following: (1) Modus Ponens [ p and [ p q q ] is a valid sentential form. (2) Affirming the consequent [ q and [ p q p ] is not a valid form. (3) All sentences of the form [ p p are logical truths. UCB Philosophy Chapter 3 (Contd) 06/02/10 Branden Fitelson Philosophy 12A Notes 5 Chapter 3 Semantics of LSL: Truth Functions VIII Here are all of the 16 possible binary truth-functions. Ive given them all names or descriptions. [Only a few of these names were made up by me.] p q nand p fi ( ) q nor niff q nfi p nif &...
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- Fall '06