Arguments in Philosophy: Understanding Validity and Soundness - Prof. Fred Feldman, Study notes of Introduction to Philosophy

Download Arguments in Philosophy: Understanding Validity and Soundness - Prof. Fred Feldman and more Study notes Introduction to Philosophy in PDF only on Docsity! Philosophy 100A Handout CI-2 Introduction to Philosophy Spring, 2009 Arguments An argument is a sequence of sentences, the last of which (the conclusion) is supposed to follow from the others (the premises). Some Sample Arguments A. 1. The Bible says that God exists. 2. If the Bible says that God exists, then God exists. 3. Therefore, God exists. B. 1. If the Bible says that God exists, then God exists. 2. The Bible says that God exists. 3. Therefore, God exists. C. 1. The Bible says that Porky Pig exists. 2. If the Bible says that Porky Pig exists, then Porky Pig exists. 3. Therefore, Porky Pig exists. D. 1. The Bible says that Porky Pig exists. 2. The Bible is the word of God. 3. Therefore, Porky Pig exists. D1: Argument A is valid =df. in virtue of A's logical form, A's conclusion must be true, if A's premises are all true. D2: Argument A is sound =df. (1) A is valid, and (2) all of A's premises are true. Some Common Valid Argument Forms Modus Ponens 1. P 1. if P, then Q 2. if P, then Q 2. P 3. therefore, Q 3. therefore, Q Multiple Modus Ponens Modus Tollens 1. P 1. if P, then Q 2. if P, then Q 2. not-Q 3. if Q, then R 3. therefore, not-P 4. therefore, R