More than a year ago, the city announced that police would crack down on illegally parked cars and that resources wou...

Naz May 4, 2014

Here we have a Strengthen with Necessary Premise question. Remember that a premise is necessary for a conclusion if and only if the falsity of the premise guarantees or brings about the falsity of the conclusion. First we check to see if the answer choice strengthens the passage, and then, if it does strengthen, we negate the answer choice to see if its negation makes the argument fall apart. If the answer choice does both those things then it is our correct answer.

The conclusion of this argument is: "the excuse about resources being tied up in fighting drug-related crime simply is not true." Why? Because no crackdown on illegally parked cars has taken place, and even though the police chief claims "that resources have had to be diverted from writing speeding tickets to combating the city's staggering drug problem," the police are "still writing as many speeding tickets as ever."

The argument is making a big leap from the premise to the conclusion. No explanation is given as to why merely because the police are still writing as many speeding tickets as ever, the excuse about the resources being tied up in fighting drug-related crime is not true.

Let's take a look at how answer choice (E), i.e. "the police cannot continue writing as many speeding tickets as ever while diverting resources to combating drug-related crime," strengthens the argument. The passage tells us that the police are still writing as many speeding tickets as ever. Thus, if we assume answer choice (E), we know that resources cannot be diverted to combating drug-related crime. So, our conclusion, "the excuse about resources being tied up in fighting drug-related crime simply is not true," is strengthened.

The next prong we must fulfill is negating the answer choice to see if its negation makes the argument fall apart. The negation of answer choice (E) is: "the police can continue writing as many speeding tickets as ever while diverting resources to combating drug-related crime." Now, if this were true, then our conclusion is not necessarily true because the police could both write as many speeding tickets as ever and also divert resources to combating drug-related crime. Thus, if the negation of answer choice (E) were assumed, it would make our argument fall apart because the police's excuse could still be true.

So, both prongs are satisfied and we know that answer choice (E) is correct.

Hope that was helpful! Please let us know if you have any other questions.

Akhil December 18, 2018

Could someone explain better by using all the answer choices? I need to understand why the other options are wrong

Ravi December 18, 2018

@Akhil,

Happy to help! Since this is a strengthen with a necessary premise question, we're looking for an answer choice that is required in order for the argument to have a chance at being valid. It's important to remember that necessary premises, unlike sufficient premises, do not 100% guarantee the conclusion.

In checking the answer choices, we can negate each and see what would happen to the argument if the negation of each answer choice were true. If the negation of an answer choice wrecks the argument, then we know that answer choice is a necessary premise. The reason we know this is because the negation of the premise effectively 'removes' that premise from the argument, so we can see just how essential it is.

Answer choice (A) states, "Every member of the police force is qualified to work on combating the city's drug problem"

The negation of this is that not every member of the police force is qualified to work on combating the city's drug problem.

O.K. What if the negation is true? Does that wreck our argument? No, it doesn't. The conclusion of the argument could still be true if this negation were true.

Answer choice (B) states, "Drug-related crime is not as serious a problem for the city as the police chief claims it is"

The negation of this is that drug-related crime is as serious a problem for the city as the police chief claims it is.

If this negation were true, our argument could still be true, so it does not completely wreck it. Whether or not drug-related crime is a serious problem for the city does not impact the overall argument in the stimulus.

Answer choice (C) states, "writing speeding tickets should be as important a priority for the city as combating drug-related crime"

The negation of this is that writing speeding tickets should not be as important a priority for the city as combating drug-related crime. This negation does not wreck the argument. The importance of writing speeding tickets vs. combating drug-related crime isn't the issue; what we're concerned with is whether or not a transfer of resources has actually happened.

Answer choice (D) states, "the police could be cracking down on illegally parked cars and combating the drug problem without having to reduce writing speeding tickets"

The negation of this is that the police cannot necessarily crack down on illegally parked cars and combat the drug problem without having to reduce writing speeding tickets.

This negation doesn't wreck the argument because the argument has already stated that no crackdown on illegally parked cars has occurred. Therefore, whether or not the police could simultaneously crack down on illegally parked cars while combating the drug problem does not impact the argument.

As Naz discusses above, (E) is a necessary premise because its negation would make the argument fall apart. If the police can continue writing as many speeding tickets as ever while diverting resources to combating drug-related crime, then the argument wouldn't hold because the police could write as many speeding tickets as ever while diverting resources to combat drug-related crime.

Hope this helps. Let us know if you have more questions!