Practice question · Numerical answer
Of the four classic conditional argument forms — modus ponens, modus tollens, affirming the consequent, denying the antecedent — how many are valid?
Hints
- Two of the four are valid forms and two are formal fallacies.
- Modus ponens and modus tollens are the valid pair.
Show the answer
2
Why
Two: modus ponens and modus tollens. Affirming the consequent and denying the antecedent are formal fallacies, and they are common precisely because they so closely resemble the valid pair.
Practise Arguments, Validity and Soundness
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More questions on Arguments, Validity and Soundness
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