In this video, Julianne Chung (Yale University) explains the philosophical concepts of truth and validity before going on to illustrate how truth and falsity, as well as validity and invalidity, can appear in various combinations in an argument. She then introduces the concept of a sound argument (i.e., a valid argument whose premises are all […]

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In this Wireless Philosophy video, Paul Henne (Duke University) discusses the philosophical concept of validity. After reviewing the structure of an argument, he defines validity: an argument is valid if and only if its premises guarantee the conclusion. He reviews a few examples of validity and invalidity, and he leaves you with one example to […]

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A description of Rule IV for validity for categorical syllogisms that negative conclusions must be drawn from negative premises and negative premises must illicit negative conclusions.(90 Second Philosophy & 100 Days of Logic)

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An explanation of the third rule of validity for categorical syllogisms, that at least one premise must be affirmative (90 Second Philosophy & 100 Days of Logic).

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A description of the Illicit Minor and Illicit Major Fallacies which break the second rule of validity for categorical syllogisms (90 Second Philosophy & Fallacy February).

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In this interview, Christopher Gauker discusses his conception of language and meaning. He also explains why universal instantiation is an invalid rule of inference in logic, why “if-then” is not the material conditional, and why beliefs are not fundamental in explaining action.

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