Test 2

Test 2 - An argument is a system of propositions: a set of...

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An argument is a system of propositions : a set of premises advanced in support of a conclusion Argument Assessment o Assessing (or evaluating) and argument is attempting to determine how good the argument is o Reconstructing an argument is representing it in standard form as clearly and comprehensively as possible Inductive and Deductive Arguments Inductive Arguments o Attempt to show that the conclusion is probable given the premises o Forcefulness o Inductive Soundness Deductive Arguments o Attempt to show that the conclusion is necessary/ guaranteed given the premises o Validity o Soundness Discussion: Our goals when arguing Our goals when arguing, if we are critical thinkers Principle of Charity o The principle of charity says that we should give the best possible representation of the other person’s argument Why? o If an argument fails, we can neither conclude that its conclusion is true or false o Its possible for a failed argument to have a true conclusion o A successful argument either guarantees that the conclusion is true or shows that the conclusion is likely o Its not nice to be uncharitable How to follow the principle of charity o Make implicit premises explicit: o Test case: McCloud is in the house, so there is beagle in the house o Pay attention to context: o Test case: there is no way to get to the moon, and you cant be on the moon unless you got there somehow, so James cant be on the moon Making implicit premises explicit 1) McCloud is a beagle 2) McCloud is in the house C) So, a beagle is in the house
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Discussion: A tension between charitableness and accuracy? Truth – the way things are o To make a claim is also to assert that its true o “John is lecturing” is equivalent to “it is true that John is lecturing” o There are two truth values, true and false o When we talk about the truth value of a proposition, we are just talking about the proposition being true or false Why? o The term “true” is useful o Shorthand o Groups of claims o Talking about claims that we have not heard but which we know are from a reliable source o Talking about claims in general Evaluating Arguments (Terminology) o Deductive arguments: o Valid o Invalid o Sound o Unsound o Propositions: o True o False o Probably/ improbable o Possible/ impossible A single proposition can be true or false, but not valid or invalid; an argument can be valid or invalid, but not true or false. Example of a Valid Argument 1) If my car runs, then my car has gas 2) My Car runs C) Therefore, my car has gas Example of an Invalid Argument 1) If my car runs, then my car has gas 2) My car has gas C) Therefore, my car runs
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Deductive Validity : o An argument is deductively valid if and only if it is impossible for all of the premises to be true and for conclusion to be false o An argument is deductively valid if and only if the conclusion is true if all of the premises are true The only case in which an argument cannot be valid is the case when the premises are all (actually) true, but the conclusion is (actually) false. Judging Validity
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Test 2 - An argument is a system of propositions: a set of...

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