determine which arguments are valid
2. The Lakers almost didn’t beat the Kings. They’ll never get past Dallas.
3. If the butler had done it, he could not have locked the screen door.
Therefore, since the door was locked, we know that the butler is in the clear.
5. Hey, he can’t be older than his mother’s daughter’s brother. His mother’s daughter has only one brother.
6. Moscone will never make it into the state police. They have a weight limit, and he’s over it.
8. I guess he doesn’t have a thing to do. Why else would he waste his time watching daytime TV?
9. “There are more injuries in professional football today than there were twenty years ago,” he reasoned. “And if there are more injuries, then today’s players suffer higher risks. And if they suffer higher risks, then they should be paid more. Consequently, I think today’s players should be paid more,” he concluded.
2. Kera, Sherry, and Bobby were all carded at JJ’s, and they all look as though they’re about thirty. Chances are I’ll be carded too.
3. Seventy percent of freshmen at Wharfton College come from wealthy families; therefore, probably about the same percentage of all Wharfton College students come from wealthy families.
5. A cut in the capital gains tax will benefit wealthy people. Marietta says her family would be much better off if capital gains taxes were cut, so I’m sure her family is wealthy.
6. According to Nature, today’s thoroughbred racehorses do not run any faster than their grandparents did. But human Olympic runners are at least 20 percent faster than their counterparts of fifty years ago. Most likely, racehorses have reached their physical limits but humans have not.
8. “Let me demonstrate the principle by means of logic,” the teacher said, holding up a bucket. “If this bucket has a hole in it, then it will leak. But it doesn’t leak. Therefore, obviously it doesn’t have a hole in it.”
9. I know there’s a chance this guy might be different, but the last person we hired from Alamo Polytech was a rotten engineer, and we had to fire him. Thus I’m afraid that this new candidate is somebody I just won’t take a chance on.
http://www.google.com/search?q=fallacies&rls=com.microsoft:en-us:IE-SearchBox&ie=UTF-8&oe=UTF-8&sourceid=ie7&rlz=1I7GGIH_en
Let us know what you think.
To determine which arguments are valid, we need to assess whether the conclusion logically follows from the premises. Here is an analysis of each argument:
2. The Lakers almost didn’t beat the Kings. They’ll never get past Dallas.
This argument is invalid because the conclusion "They'll never get past Dallas" does not logically follow from the premise "The Lakers almost didn't beat the Kings." The premise only suggests that the Lakers had a difficult time against the Kings, but it doesn't provide enough evidence to conclude that they will never get past Dallas.
3. If the butler had done it, he could not have locked the screen door. Therefore, since the door was locked, we know that the butler is in the clear.
This argument is valid. The conclusion logically follows from the premise. If the butler could not have locked the screen door if he had done it, and the door was locked, then it follows that the butler is in the clear.
5. Hey, he can’t be older than his mother’s daughter’s brother. His mother’s daughter has only one brother.
This argument is valid. The conclusion follows from the premise. If his mother only has one brother, then the person in question can't be older than that brother.
6. Moscone will never make it into the state police. They have a weight limit, and he’s over it.
This argument is valid. The conclusion logically follows from the premise that there is a weight limit for the state police and Moscone is over it.
8. I guess he doesn’t have a thing to do. Why else would he waste his time watching daytime TV?
This argument is invalid. The conclusion does not logically follow from the premise. Just because someone is watching daytime TV does not necessarily mean they have nothing else to do. There could be various reasons why someone chooses to watch daytime TV.
9. “There are more injuries in professional football today than there were twenty years ago,” he reasoned. “And if there are more injuries, then today’s players suffer higher risks. And if they suffer higher risks, then they should be paid more. Consequently, I think today’s players should be paid more,” he concluded.
This argument is valid. The conclusion logically follows from the premises. If there are more injuries in professional football, and higher risks for players as a result, it follows that they should be paid more.
2. Kera, Sherry, and Bobby were all carded at JJ’s, and they all look as though they’re about thirty. Chances are I’ll be carded too.
This argument is invalid. The conclusion does not logically follow from the premise. Just because Kera, Sherry, and Bobby were carded and look around thirty does not guarantee that the person making the argument will be carded.
3. Seventy percent of freshmen at Wharfton College come from wealthy families; therefore, probably about the same percentage of all Wharfton College students come from wealthy families.
This argument is valid. The conclusion logically follows from the premise. If seventy percent of freshmen come from wealthy families, it is likely that a similar percentage of all Wharfton College students come from wealthy families.
5. A cut in the capital gains tax will benefit wealthy people. Marietta says her family would be much better off if capital gains taxes were cut, so I’m sure her family is wealthy.
This argument is invalid. The conclusion does not logically follow from the premise. Just because a cut in the capital gains tax benefits wealthy people and Marietta's family would be better off doesn't necessarily mean her family is wealthy.
6. According to Nature, today’s thoroughbred racehorses do not run any faster than their grandparents did. But human Olympic runners are at least 20 percent faster than their counterparts of fifty years ago. Most likely, racehorses have reached their physical limits but humans have not.
This argument is valid. The conclusion logically follows from the premises. If today's thoroughbred racehorses don't run any faster than their grandparents, but human Olympic runners are faster than their counterparts of fifty years ago, it is reasonable to conclude that racehorses have reached their physical limits while humans have not.
8. “Let me demonstrate the principle by means of logic,” the teacher said, holding up a bucket. “If this bucket has a hole in it, then it will leak. But it doesn’t leak. Therefore, obviously it doesn’t have a hole in it.”
This argument is invalid. The conclusion does not logically follow from the premises. Just because the bucket doesn't leak doesn't necessarily mean it doesn't have a hole. It could have been patched or there could be other explanations.
9. I know there’s a chance this guy might be different, but the last person we hired from Alamo Polytech was a rotten engineer, and we had to fire him. Thus I’m afraid that this new candidate is somebody I just won’t take a chance on.
This argument is invalid. The conclusion does not logically follow from the premises. Just because the last person hired from Alamo Polytech was a rotten engineer doesn't mean that the new candidate from the same institution will also be bad. The premise does not provide enough evidence to support the conclusion.