Comprehension Questions

a. What does the word “valid” mean?      b. If an argument is valid, must its premises be true? Using the concepts discussed in this chapter, explain your answer. Give an example.      c. If an argument has false premises, must it be invalid? If not, give an example?

Using the following proposition as a conclusion, “Tofu is delicious,” construct two arguments:

a.       One that is valid and has two false premises             b. One that is invalid with two true premises

Using the validity test, assess whether each of these arguments is valid.

a. Cats are warm-blooded and warm-blooded animals are mammals, so cats are mammals.

b. The table is blue, so it is colored.

c. The War of Independence was a revolution, and revolutions are morally wrong, so the War of Independence was morally wrong.

d. If a plant dries out it will die. This plant is all dried out. So it will die.

e. I should make dinner. It is my turn and my wife and I take turns.

f. The cat is asleep. Cats always dream when they are asleep, so he is dreaming now. g. 2 + 2 = 4 and 4 + 4 = 8, so 2 + 2 + 4 = 8.

h. Lying to someone is like robbing them of the truth, and robbing is wrong, so lying is wrong too.

i. The movie was terrible. It was too long and the theatre was way too overcrowded.

j. Running helps to build cardiovascular strength and can extend your life. Anything that has these effects is good for you, so running is good for you.