Counterexample Hunter

Pick an argument form and hunt for a counterexample: set P, Q (and R) to true or false until every premise is true and the conclusion is false. Find one, and the form is invalid. If none exists, the form is valid. Then put your counterexample into words.

Choose a form

Fallacies from the course

Valid forms

The form

Set the truth values

Put it into words

A form is invalid if even one row of its truth table has all premises true and the conclusion false. That row is the counterexample, and any real sentences with those truth values give you one in plain English.