Copyright © 1997, Norman Swartz
Department of Philosophy
Simon Fraser University

Answers to the
Second Set of Practice Exercises
on Necessary Conditions and Sufficient Conditions

1. LSC
   
   
2. LNC
   
   
3. LSC
   
   
4. LNC & LSC
   
   
5. X (Alice may have a brother-in-law, not because she has a sister who is married, but because her husband's sister is married.)
   
   
6. LSC
   
   
7. X
   
   
8. LSC
   
   
9. LNC
   
   
10. LNC
    
    
11. LNC & LSC
    
    
12. X
    
    
13. X
    
    
14. LSC
    
    
15. LNC

16. LNC & LSC
    
    
17. LNC & LSC
    
    
18. X
    
    
19. LNC
    
    
20. LNC
    
    
21. X
    
    
22. X
    
    
23. LSC
    
    
24. X
    
    
25. LSC
    
    
26. X (Statement 26(a) does not tell us whether there is any other fruit in Sue's basket. Perhaps there are also four grapefruits in Sue's basket.)
    
    
27. X (Statement 27(a) says merely that there are two apples and two oranges in Sue's basket. It doesn't tell us that the fruit belongs to Sue. Perhaps someone has borrowed Sue's basket, and the fruit in the basket belongs to the borrower.)