The scope of logic
Marking arguments valid or invalid, then settling which combinations of true premises, false premises and false conclusions a valid argument can have.
2 exercises
Exercise A
Which of the following arguments is valid? Which is invalid?
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Socrates is a man.
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All men are carrots.
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Socrates is a carrot.
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Abe Lincoln was either born in Illinois or he was once president.
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Abe Lincoln was never president.
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Abe Lincoln was born in Illinois.
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If I pull the trigger, Abe Lincoln will die.
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I do not pull the trigger.
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Abe Lincoln will not die.
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Abe Lincoln…
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Exercise B
Could there be:
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A valid argument that has one false premise and one true premise?
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A valid argument that has only false premises?
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A valid argument with only false premises and a false conclusion?
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An invalid argument that can be made valid by the addition of a new premise?
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A valid argument that can be made invalid by the addition of a new premise?
In each case: if so, give an example; if…
Adapted from forall x: Calgary © 2025 P. D. Magnus, Tim Button, Robert Trueman, and Richard Zach. Licensed under CC BY 4.0. Source: forall x: Calgary. Imported at revision ec34df8.