1. Copyright © 2014, 2010, 2007 Pearson Education, Inc. Section 3.4, Slide 1 3 Logic The Study of What’s True or False or Somewhere in Between 3

2. Copyright © 2014, 2010, 2007 Pearson Education, Inc. Section 3.4, Slide 2 Verifying Arguments3.4 Use truth tables to show an argument to be valid Understand how a truth table can show an argument to be invalid (continued on next slide)

3. Copyright © 2014, 2010, 2007 Pearson Education, Inc. Section 3.4, Slide 3 Verifying Arguments3.4 Recognize some common valid argument forms Recognize some common fallacies

4. Copyright © 2014, 2010, 2007 Pearson Education, Inc.Section 3.4, Slide 4 Verifying Arguments Representations of arguments:

5. Copyright © 2014, 2010, 2007 Pearson Education, Inc.Section 3.4, Slide 5 Verifying Arguments Truth table for Because this statement is a tautology, the argument is valid. The form is called the law of detachment.

6. Copyright © 2014, 2010, 2007 Pearson Education, Inc.Section 3.4, Slide 6 Verifying Arguments

7. Copyright © 2014, 2010, 2007 Pearson Education, Inc.Section 3.4, Slide 7 Verifying Arguments Example: (solution on next slide)

8. Copyright © 2014, 2010, 2007 Pearson Education, Inc.Section 3.4, Slide 8 Verifying Arguments Example: (solution on next slide) Symbolically:

9. Copyright © 2014, 2010, 2007 Pearson Education, Inc.Section 3.4, Slide 9 Verifying Arguments Solution: is called the law of contraposition.

10. Copyright © 2014, 2010, 2007 Pearson Education, Inc.Section 3.4, Slide 10 Invalid Arguments Example: (solution on next slide)

11. Copyright © 2014, 2010, 2007 Pearson Education, Inc.Section 3.4, Slide 11 Invalid Arguments Example: (solution on next slide) Symbolically:

12. Copyright © 2014, 2010, 2007 Pearson Education, Inc.Section 3.4, Slide 12 Verifying Arguments Solution: One or more F’s in the truth table means the argument is invalid.

13. Copyright © 2014, 2010, 2007 Pearson Education, Inc.Section 3.4, Slide 13 Verifying Arguments is called the fallacy of the converse.

14. Copyright © 2014, 2010, 2007 Pearson Education, Inc.Section 3.4, Slide 14 Valid Argument Forms and Fallacies

15. Copyright © 2014, 2010, 2007 Pearson Education, Inc.Section 3.4, Slide 15 Verifying Arguments Example: Identify the form of the argument and state whether it is valid. Solution:

16. Copyright © 2014, 2010, 2007 Pearson Education, Inc.Section 3.4, Slide 16 Verifying Arguments Example: Identify the form of the argument and state whether it is valid. Solution:

17. Copyright © 2014, 2010, 2007 Pearson Education, Inc.Section 3.4, Slide 17 Verifying Arguments Example: Identify the form of the argument and state whether it is valid. Solution:

18. Copyright © 2014, 2010, 2007 Pearson Education, Inc.Section 3.4, Slide 18 Verifying Arguments Example: Identify the form of the argument and state whether it is valid. Solution: