Category:
Definition: Any argument of the form: If A then B, Not A, thus Not B
Examples:
Proof:
Any argument of the following form is invalid:
If A happens then B will happen (First premiss)
A did not happen. (Second premiss)
Therefore, B did not happen. (Conclusion)
Show that even though the premises are true, the conclusion may be false. In particular, show that the consequence B may occur even though A does not occur. (Barker: 69, Cedarblom and Paulsen: 26, Copi and Cohen: 241)