Causal Reasoning

Answers

1. C is sufficient since any time it is present, the target G is present. Both C and D are necessary, since any time the target G is present, they are present.
   
2. A and C are sufficient; A and C are also necessary.
   
3. C and D are necessary. All candidates are sufficient, since there is never a case where a candidate is present but the target is absent. However, the test for sufficient conditions is not rigorous, since there is no case in which the target is absent (hence, it is trivially true that there is no case in which a candidate is present when the target is absent).
4. No one candidate is sufficient (case 1 rules them all out). Only C is necessary.
   
5. C is sufficient; B, C, and D are necessary.
   
6. None are sufficient (case 1 rules them all out); A and D are necessary.
   
7. B is sufficient; A, B and D are necessary.
   
8. C is sufficient; A, B, C, and D are all necessary. However, the test for necessary conditions is not rigorous, since there is no case in which the target is present (hence, it is trivially true that there is no case in which a candidate is absent when the target is present).
   
9. B and C are sufficient; C and D are necessary.
   
10. A and C are sufficient; D is necessary.