lecture 4 - Logic and Reasoning [4] PHIL 102 31 Aug...

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Unformatted text preview: Logic and Reasoning [4] PHIL 102 31 Aug [email protected] Office hours: Wed 3-4:50 200A Gregory Hall *Check the Compass website frequently!* Homework b not graded, no deadline b some exercises discussed Friday b your responsibility b troubles? Reach out! RECAP Chapter 1: what CT is good for? How to do it? Chapter 2: what are the obstacles to CT? How can we overcome them? Key terms and concepts From now on: ARGUMENTS ARGUMENTS ARGUMENTS ARGUMENTS ARGUMENTS ARGUMENTS ARGUMENTS Statement (claim): An assertion that something is or is not the case. = a proposition is (expressed by) a sentence that is true or false “Washington is the capital of the USA” “Grass is blue” Not statements (claims, propositions) : “Close the door!” (order) “Ouch” (exclamation) Statement (claim): An assertion that something is or is not the case. Premise : A statement given in support of another statement. Conclusion : A statement that premises are used to support. Argument : A group of statements in which some of them (the premises) are intended to support another of them (the conclusion) ≠ fight, quarrel, etc. An argument = a structured set of sentences premises and a conclusion All puppies are cute Bix is a puppy _ Bix is cute 5 Deductive Arguments 1. A deductive argument is intended to provide conclusive support for its conclusion. 2. A deductive argument that succeeds in providing conclusive support for its premise is said to be valid . A valid argument is such that if its premises are true, its conclusion must be true. 3. A deductively valid argument with true premises is said to be sound . Chapter 3: Making Sense of Arguments An argument is valid s if the conclusion follows from the premises s there is no way for the premises to be true and the conclusion to be false s taking the premises to hold (even if we realize they are actually false!), the conclusion follows Otherwise it is invalid . 7 An argument b valid = conclusive support Valid: Is there any way for the premises to be true and the conclusion to be false? All men are mortal Socrates is a man _ Socrates is mortal Check!...
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This note was uploaded on 12/20/2011 for the course PHIL 102 taught by Professor Rug during the Fall '11 term at University of Illinois, Urbana Champaign.

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lecture 4 - Logic and Reasoning [4] PHIL 102 31 Aug...

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