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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.

forall x: Calgary, The scope of logic

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2 exercises

Exercise A

Which of the following arguments is valid? Which is invalid?

    • Socrates is a man.

    • All men are carrots.

    • Socrates is a carrot.

    • Abe Lincoln was either born in Illinois or he was once president.

    • Abe Lincoln was never president.

    • Abe Lincoln was born in Illinois.

    • If I pull the trigger, Abe Lincoln will die.

    • I do not pull the trigger.

    • Abe Lincoln will not die.

    • Abe Lincoln…

3.0

Exercise B

Could there be:

  1. A valid argument that has one false premise and one true premise?

  2. A valid argument that has only false premises?

  3. A valid argument with only false premises and a false conclusion?

  4. An invalid argument that can be made valid by the addition of a new premise?

  5. A valid argument that can be made invalid by the addition of a new premise?

In each case: if so, give an example; if…

3.0
Other logical notions

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.

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