Exam 10: Deduction and Induction: A Closer Look

Aristotle founded his own school, known as the Lyceum.

The following is a valid argument: The Bungles is a great band. Jan is a member of the band. Therefore, Jan must be a great musician.

On critically evaluating inductive arguments. Read the following arguments and carry out the instructions below. -Consider this argument: I've eaten three times at Fabulous Freddie's Fast Food Fandango, and I liked the food each time. I'll probably like the food the next time I eat there. In each of the following cases, would the addition make the argument stronger or weaker? Or would it leave things unaffected? a. The first time I ate a burrito, the second time I ate a hamburger, the third time I ate a fishburger. b. All three previous times I ate hamburgers; this time I'm going to eat a fishburger. c. On all three previous visits, the meals were cooked by Freddie himself. The next trip, Freddie will be on vacation, and the food will be cooked by his manager, Wimpy. d. I've actually eaten there only twice. e. The next time I eat at Freddie's, I'm going to try something new: his "oysterburger." f. All three previous times I ate hamburgers; this time I'm going to eat a hamburger again. g. Since my last visit, I've become a vegan.

Think with Socrates does not contain a section on enthymemes. However, the concept can be defined briefly. This exercise defines an enthymeme and gives students a chance to practice filling in holes in incomplete deductive arguments. An enthymeme is an argument that is missing one or more premises or a conclusion. Each of the following deductive arguments is missing either a premise or a conclusion. (Thus, each is an enthymeme.) Add a statement to each so as to turn the enthymeme into a valid argument. -If we drive to Portland, then we'll see the Willamette River. If we drive to Yakima, then we'll see the Yakima River … Therefore, either we'll see the Willamette or the Yakima.

Assume each of the following is a deductive argument. In each case, is the argument valid or invalid? (V or I) -All aardvarks are cute critters. All cute critters are lovable. So all aardvarks are lovable.

The following is a valid argument: It is raining. Therefore, it is raining.

The following is a valid argument: Ann is good at math. All chemists are good at math. Therefore, Ann is a good chemist.

The following is a strong argument: Joe has eaten lunch at the taco stand every day for three days straight. Thus, tomorrow he will probably eat there again.

If an argument is cogent, then it is also strong.

All sound arguments are valid arguments.

On deductive arguments. -If an argument is deductively valid, then it is also sound.

Think with Socrates does not contain a section on enthymemes. However, the concept can be defined briefly. This exercise defines an enthymeme and gives students a chance to practice filling in holes in incomplete deductive arguments. An enthymeme is an argument that is missing one or more premises or a conclusion. Each of the following deductive arguments is missing either a premise or a conclusion. (Thus, each is an enthymeme.) Add a statement to each so as to turn the enthymeme into a valid argument. -If Joe wins the game, then he will be rich. So he will be rich.

The following is a weak argument: Joe hasn't eaten lunch at the taco stand for sixty days straight. Thus, tomorrow he will probably not eat there again.

An analogical argument is inductive in nature.

On deductive arguments. -If an argument is valid, then it must have all true premises.

The following is a valid argument: Senator Clarke is a bad man. Therefore, the argument he just gave on the floor of Congress must be a bad argument.

Assume each of the following is a deductive argument. In each case, is the argument valid or invalid? (V or I) -No aardvarks are reptiles. No reptiles are blue. So no aardvarks are blue.

The text divides all arguments into these very general categories:

The following is a weak argument: Joe hasn't eaten lunch at the taco stand for sixty days straight. Thus, tomorrow he will probably eat there.

Strong or Weak? -The last time I went to Spud's Fish 'n' Chips with Katrina, she ordered a large diet Coke. We are going to eat there again tonight. She will probably order a large diet Coke.