Unformatted text preview: Modus Tollens If P then Q. Not Q. Therefore, not P. Example: If the earth were flat, the hull of a receding ship would not disappear before the sails. The hull of a receding ship does disappear before the sails. Therefore, the earth is not flat. Two invalid argument forms: Denying the Antecedent If P then Q. Not P. Therefore, not Q. Example: If I owned all the gold in Fort Knox, I would be wealthy. I do not own all the gold in Fort Knox. Therefore, I am not wealthy. Affirming the Consequent If P then Q. Q. Therefore, P. Example: If Jones is gay, he supports gay rights. Jones supports gay rights. Therefore, Jones is gay....
View
Full Document
 Fall '07
 Gustafson
 Logic, Modus ponens, Modus tollens, Affirming the consequent, Argument form

Click to edit the document details