Question

WEEK #6: VALIDITY, STRENGTH, AND

DETERMINING WHETHER ARGUMENTS ARE INDUCTIVE OR DEDUCTIVE

ASSIGNMENT 1:

A. Determine whether the following deductive arguments are valid or invalid.

1. New York City is either in the U.S.A. or France. But it's not in France. It follows that New York City is in France.

2. If the moon is made of green snot, then there are boogers on the moon. The moon is made of green snot; therefore, there are boogers on the moon.

3. If a car is made by FORD, then it comes with a warranty. Corvette cars are not made by FORD. Therefore, Corvette cars do not come with a warranty.

B. Determine whether the following inductive arguments are strong or weak.

1. The Governor of the state of Michigan has stated that the water supply of Flint (a city in Michigan) does not constitute a major threat to the public health. Furthermore, his Cabinet members agree with him on this point. Accordingly, we conclude that the water supply of Flint (a city in Michigan) does not constitute a major threat to the public health.

2. Two weeks after Pope Francis visited Mexico City to warn against the ills of drug-trafficking and violence, the city suffered a severe earthquake. Therefore, Pope Francis caused the severe quake in Mexico City.

3. 45 million turkeys are killed each year for Thanksgiving. Therefore, the next turkey killed is certain to be for Thanksgiving.

ASSIGNMENT 2:

Determine whether the following arguments are inductive or deductive and correspondingly valid/invalid or strong/weak.

1. Most birds can fly, and an ostrich is a bird.   So, ostriches most probably can fly.

2. If the Taliban take power in Afghanistan, then they will eventually take power in all Central Asia. And, if the Taliban take power in all Central Asia, then they will take over the rest of the world. Thus, once the Taliban take power in Afghanistan, they will take over the rest of the world.

3. Either Maria will earn an A in this logic course or she will earn a B, C, D, E, or I. Maria did not earn a B, C, D, E, or I. So, she must have earned an A.

Answer 1

A. Determine whether the following deductive arguments are valid or invalid.

1. New York City is either in the U.S.A. or France. But it's not in France. It follows that New York City is in France.

Answer) Invalid

2. If the moon is made of green snot, then there are boogers on the moon. The moon is made of green snot; therefore, there are boogers on the moon.

answer) Valid

3. If a car is made by FORD, then it comes with a warranty. Corvette cars are not made by FORD. Therefore, Corvette cars do not come with a warranty.

Answer) Valid

B. Determine whether the following inductive arguments are strong or weak.

1. The Governor of the state of Michigan has stated that the water supply of Flint (a city in Michigan) does not constitute a major threat to the public health. Furthermore, his Cabinet members agree with him on this point. Accordingly, we conclude that the water supply of Flint (a city in Michigan) does not constitute a major threat to the public health.

Answer) Strong

2. Two weeks after Pope Francis visited Mexico City to warn against the ills of drug-trafficking and violence, the city suffered a severe earthquake. Therefore, Pope Francis caused the severe quake in Mexico City.

Answer) Weak, there is no correlation between the two events and the argument is not convincing

3. 45 million turkeys are killed each year for Thanksgiving. Therefore, the next turkey killed is certain to be for Thanksgiving.

Answer) Weak,it is not convincing, there are various reasons for turkeys to be killed

Determine whether the following arguments are inductive or deductive and correspondingly valid/invalid or strong/weak.

1. Most birds can fly, and an ostrich is a bird.   So, ostriches most probably can fly.

Answer)  This argument is inductive because the conclusion is not with certainty, but likely. Since the argument is inductive, then the argument is also invalid. The argument is strong because most is a high percent and most birds can fly. If you didn’t know that ostriches can’t fly, you would believe they might since an ostrich is a bird and most birds fly.

2. If the Taliban take power in Afghanistan, then they will eventually take power in all Central Asia. And, if the Taliban take power in all Central Asia, then they will take over the rest of the world. Thus, once the Taliban take power in Afghanistan, they will take over the rest of the world.

Answer) This is a deductive argument that follows hypothetical syllogism (chain argument). It is a valid argument because it follows hypothetical syllogism and the premises follow logically. The conclusion is based on the logic of the premises so truth is preserved.

3. Either Maria will earn an A in this logic course or she will earn a B, C, D, E, or I. Maria did not earn a B, C, D, E, or I. So, she must have earned an A.

Answer) This is a deductive argument that follows Modus Tollens. Based on the premises and conclusion this is a valid argument. The conclusion is based on the logic of the premises so truth is preserved.