[ Up ] [ Assignment # 1 ] [ Logic SG 1 ] [ Casting Arguments Assignment ] [ Logic SG 2 ] [ Assignment 3a ] [ Class Exercise on Arguments with Hypothetical Premises ] [ Assignment 3b ] [ Logic SG 3 ] [ Analyzing Miscellaneous Arguments ] [ Exercise on Miscellaneous Arguments ] [ Assignment 4 ] [ Logic SG 4 ] [ Fallacy Indentification Practice ] [ Fallacy Practice -10 ] [ Assignment 5 ] [ Logic SG 5 ] [ Assignment 6 ] [ Logic SG 6 ]

 

 

Arguments with Hypothetical and Disjunctive Premises

Assignment 3b

 

For the next six arguments,

  1. Formalize the argument. (Hint: Remember that in this type of argument, letters are used to represent entire statements, not categories.)
  2. Name the argument form. (Modus ponens, modus tollens, hypothetical syllogism, disjunctive syllogism, fallacy of denying the antecedent, or fallacy of asserting the consequent are the forms in question.)
  3. State whether the argument is valid or invalid.

 

  1. If Jack had studied logic (L), he would win all arguments with his friends (W). Since Jack does win all arguments with his friends, it is apparent that Jack has studied logic.
  2. If the factory had shut down last year (F), Joan would have lost her job (L). Since Joan didn't lose her job, the factory must not have shut down.






  3. Rosa will either work late (W) or she will study for the test (S). Since Rosa didn't work late, she did study for the test.
  4. If Marvin passes calculus (C), he will become a physics major (P). If he becomes a physics major, he won’t take any more art classes (A). Thus, if Marvin passes calculus, he won’t take any more art classes.
  5. If Maggie discovers a new species of ants in the Amazon rain forest (D), she will be famous. (F) However, since she did not succeed in discovering a new species of ant, Maggie will not be famous.

 

 

 

Truth tables

 

 

6. If he loves her (L), he will marry her (M). But he doesn’t love her. Thus, he will not marry her.

Formalize:

 

 

Construct a truth table:

                                         Premise 1                   Premise 2                           Conclusion

L

M

          

             
             
             

Is this argument valid or invalid? Show why on the truth table.

 

 

 

7. Ellen is at work (W) or Ellen is fishing (F). If Ellen’s fishing rod is on the porch (P), then Ellen didn’t go fishing. Her fishing rod is on the porch. Thus, Ellen is at work.

Formalize:

Construct a truth table:

                                                         Premise 1            Premise 2             Premise 3                 Conclusion

W

F

P

            
                 
                 
                 
                 
                 
                 
                 
                 

Is this argument valid or invalid? Show why on the truth table.

 

 

Author:  Holly Graff
Oakton Community College
Updated: October 11, 2001