May_5_slides - Tuesday, May 5 Today we'll cover: 1.2 Review...

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Tuesday, May 5 Today we'll cover: - 1.2 Review of propositions - 1.2 Discussion of arguments - 1.3 Recognizing arguments - 1.4 Arguments and explanations - 1.5 Deductive and inductive arguments - 1.6 Validity and truth At each step, we'll try and do a few examples
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1.2 Propositions Are sentences that assert something; the most important feature of propositions is that they and only they are true or false We often speak of sentences as having “propositional content” - the proposition the sentence expresses. Different sentences can have the same propositional content. Questions (“Where are you?”), commands (“Get yourself together!”), and exclamations (“Ouch!”) are NOT propositions Examples of propositions: “It is raining”, “The moon is smaller than a nickel”, “I wrote this at the Fyxx near St. Vital Centre”
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Propositions (con't) Note that there are simple and compound propositions - Simple: asserts a single indivisible idea like “That is a dog.” - Note that simple propositions can be complex or wordy like: “The worm-eaten peach fell turning end over end with a gentle slow motion” which is still a simple proposition; “It was big and red”, however, can be split into two components (“It was big.” and “It was red.”), and is thus compound
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Propositions (con't) There are roughly three kinds of compound propositions: 1) Conjunctive - “and” (such as “It is big and red”, as above) 2) Disjunctive - “or” (“It is big or red”) 3) Hypothetical - “if-then” (“If it is big, then it is red.”)
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1.2 Arguments An argument is made up of propositions in order to persuade The propositions are arranged such that some one proposition is affirmed based on the support given by some other propositions, i.e., one proposition rests on the others. The supporting propositions are called premises ; the supported proposition (which the argument aims toward) is called the conclusion A good argument has a conclusion that any rational being would infer from the premises – which is to say, if you accept the premises, you'll have to accept the conclusion.
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Arguments (con't) A good argument, then, has a series of premises arranged such that together, they support the conclusion, to the extent that ideally accepting the premises makes the conclusion necessary. Consider two examples: P1 If it is raining, then the streets will be wet. P2 It is raining.
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This note was uploaded on 01/08/2010 for the course ME 310 taught by Professor Lwonard during the Spring '09 term at University College Cayman Islands.

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May_5_slides - Tuesday, May 5 Today we'll cover: 1.2 Review...

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