Valid (false premises, true conclusion)

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Validity is always hypothetical: what IF the premises are true, would the conclusion HAVE to be true? Can I IMAGINE circumstances where the premises are true and the conclusion false? In the case of an argument which actually has false premises, it takes a short story or fictional work to do this. Such an argument is UNSOUND because the argument does NOT have true premises.



For either example, the logic is valid but the premises are false. For the premises to be true, all of them need to be true. But, for the premises to be false, only one need be false. So, an argument with a mixture of true and false premises is still considered to be an argument with false premises--it is false that all of the premises are true. Nevertheless, in these examples, the conclusion is true.

Validity is a guarantee of a true conclusion when the premises are true but offers no guarantee when the premises are false. False premises can lead to either a true or a false conclusion even in a valid argument. In these examples, luck rather than logic led to the true conclusion.