This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: Chapter 8: Hints and Selected Solutions Section 8.1 (page 203) 8.1 1. Affirming the consequent is invalid . 4. Weakening the Antecedent invalid . 7. Constructive Dilemma is valid . 8.4 Here is an informal proof of the argument: The unicorn, if horned, is elusive and dangerous. If elusive or mythical, the unicorn is rare. If a mammal, the unicorn is not rare. The unicorn, if horned, is not a mammal. Proof. Assume that the unicorn is horned. We want to prove that it is not a mamal. Assume, by way of a proof by contra- diction, that is is a mamal. By the third premise, the unicorn is not rare. By the first premise, the unicorn is elusive. Bu then by the second premise, the unicorn is rare, after all. This gives us our contradicion, showing us that our assummption is false. 8.7 Here is an informal proof of the argument: b is small unless its a cube. If c is small, then either d or e is too....
View Full Document
This note was uploaded on 03/25/2009 for the course LOGIC 20034 taught by Professor Dhoe during the Spring '09 term at Hanover.
- Spring '09