Philosophy 251: Handout #2

I. Extract the argument(s) from each of the following passages and put the arguments into standard form.

1. Having cancer is a good, for whatever is required by something that is good is itself a good. Being cured of cancer is a good, and being cured of cancer requires having cancer.
   
   
2. Obviously, empirical data are scientific. But only what can be falsified is scientific, and so, although many people regard empirical data as fixed and unchangeable, empirical data can be falsified.
   
   
3. God predestines human acts only if God fully causes human acts. God fully causes human acts only if humans lack free will. So, God predestines human acts only if humans lack free will. But humans do not lack free will, so God does not predestine human acts.
   
   
4. It is not possible that a thing be the efficient cause of itself; for if a thing were the efficient cause of itself it would be prior to itself; but nothing is prior to itself. Also, if there be no first cause among efficient causes there will be no ultimate effect nor any intermediate cause, but it is plainly false that there is no ultimate effect or intermediate cause. Hence, the order of efficient causes cannot go on to infinity. Therefore, it is necessary to admit a first efficient cause, to which everyone gives the name God. --Thomas Aquinas
   
   
5. Either potential murderers are rational enough to be deterred by the death penalty or they are not. If not, then the death penalty is not necessary. If potential murderers are rational enough to be deterred by the death penalty, then they are rational enough to be deterred by life imprisonment, and if they are rational enough to be deterred by life imprisonment, the death penalty is not necessary. Either way the death penalty is not necessary and so should be abolished, for if the death penalty isn't necessary it should be abolished.

II. Which of the following are true and which are false? Support your answer.

Eg. 1--Valid arguments cannot have false conclusions.
Answer: False. Support: "All cats are fish / Some cats are fish" is a valid argument and yet the conclusion is false.

Eg. 2--Sound arguments must have true premises.
Answer: True. Support: According to the definition of 'sound', an argument is sound only if all the premises are true.

1. If an argument is valid, then all its premises are true.
2. Any argument with all true premises is valid.
3. All sound arguments are valid.
4. All valid arguments are sound.
5. No argument with a false conclusion is valid.
6. Every argument with a true conclusion is valid.
7. Any argument with all true premises and a true conclusion is valid.
8. Any argument with all true premises and a false conclusion is invalid.
9. A sound argument can have a false conclusion.
10. A sound argument can have a false premise.