Logic in a Nutshell

Exercise 2:  Premises and Conclusions

ASSIGNMENT I

Instructions:  Identify the premises and the conclusions in the following arguments.  Please note that an answer key has been provided for Part A.

IA.  Practice Questions

1. All spiders have six legs.  All six-legged creatures have wings.  It follows, then, that all spiders have wings.

2. If Bacon wrote Hamlet, then Bacon was a great writer.  Bacon was a great writer.  Therefore Bacon wrote Hamlet.

3. Government-funded efforts to save the whooping crane from extinction are paying off.  Therefore, government funding of programs to preserve endangered species should be continued.

4. Now human law is framed for the multitude of human beings.  But the majority of human beings are not perfect in virtue.  And so it would seem that human laws do not forbid all vices.

5. One should be extremely cautious to judge another human being, since we are all sinners.

  Answer Key for Practice Questions

IB.   Homework Assignment

1. All rational beings are responsible for their actions, and since all human beings are rational, it follows that all human beings are responsible for their actions.

2. Almost every known human carcinogen  causes cancer in animals.  Therefore, it is reasonable to expect that compounds that cause cancer in animals are also potential human carcinogens.

3. Since happiness consists in peace of mind, and since durable peace of mind depends on the confidence we have in the future, and since that confidence is based on the science we should have of the nature of God and the soul, it follows that science is necessary for happiness.

4. Old man Brown claims that he saw a flying saucer land on his farm.  But old man Brown never got beyond the fourth grade in school and can hardly read or write.  He is completely ignorant of what scientists have written on the subject, so his report cannot possibly be true.

5. If it is wrong to kill a one-month-old infant, but not a six-month fetus, there has to be some difference between them---not just some difference or other, but a morally relevant difference: there has to be something true of the six- month fetus but not of the one month old infant that makes it permissible to kill the former.  Surely, though, there is no significant developmental difference, somatic or psychological.  True, the six month old fetus is dependent upon its mother for life.  But so, normally, is the one month old infant---in a different way of course, but to no less a degree.  Therefore, if it is not wrong to kill a six-month-old fetus, it is not wrong to kill a one-month-old infant.  But the latter is wrong.  Hence so is the former.

6. It is immoral to use rabbits in cosmetic experiments, because causing pain is immoral, and animals such as rabbits are capable of feeling pain.

7. Its seems that mercy cannot be attributed to God.  For mercy is a kind of sorrow.  But there is no sorrow in God; and so there can be no mercy in him either.

8. Write your own example of an argument in the space provided below:

ASSIGNMENT II

Instructions:  Fill in the blank spaces with the appropriate premises or conclusions.  Again, an answer key has been provided for Part A.

IIA.  Practice Questions

  Answer Key for Practice Questions

IIB.   Homework Assignment