notes_4_2x2 - Branden Fitelson Philosophy 12A Notes 1...

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Unformatted text preview: Branden Fitelson Philosophy 12A Notes 1 Announcements & Such Bob Dylan : Desolation Row Administrative Stuff If you did not receive an email telling you which section you are in, then you are not going to be enrolled in the course this semester (unless we made an error, in which case, see us at end of class). Section rosters have been set (see website for times and locations). Sections with (as yet) undetermined permanent locations will meet temporarily in 301 Moses. Stay tuned for permanent locations. HW #1 (1 st sub) due Today @ 4pm @ 12A drop box (301 Moses). Introduction to the Course & Chapter 1 of Forbes Working with our official (informal/absolute) definition of validity. Absolute/Informal validity vs Formal Validity Entre to Chapter 2 The Language of Sentential Logic (LSL) UCB Philosophy Chapter 1 , Final & Chapter 2 Intro. 09/05/08 Branden Fitelson Philosophy 12A Notes 2 Informal (Absolute) Validity Our Fundamental Concept An argument is a collection of propositions , one of which (the conclusion ) is meant to follow-from the others (the premises ). From a logical point of view, an argument A is good just in case its conclusion does follow-from its premises that is, if A is valid . Our official (informal/absolute) definition of validity is as follows: Definition . A is valid iff it is ( logically !) impossible for both of the following to be true simultaneously ( i.e. , in the same situation): (1) All of A s premises are true. (2) A s conclusion is false. A more operational way of understanding the definition is as follows. Suppose that all of A s premises are true. Then, try to imagine a situation (or possible world) like that in which A s conclusion is false. If that is conceivable, then A is in valid (otherwise, A s valid). UCB Philosophy Chapter 1 , Final & Chapter 2 Intro. 09/05/08 Branden Fitelson Philosophy 12A Notes 3 Validity, Soundness, and All-Things-Considered Good Arguments A good argument is one in which the conclusion follows from the premises. But, intuitively, there is more to a good argument (all things considered) than mere validity. [But, after chapter 1, we wont care.] Ideally, arguments should also have (actually) true premises . If the premises of an argument are (actually) false, then (intuitively) the argument isnt very good (or actually useful) even if it is valid. Definition . An argument A is sound if and only if both : ( i ) A is valid, and ( ii ) all of A s premises are (actually) true. So, there are two components or aspects of good arguments: Logical Component: Is the argument valid?...
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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.

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notes_4_2x2 - Branden Fitelson Philosophy 12A Notes 1...

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