LSAT-Section-1-Logical-Reasoning – Section One : Logical Reasoning

Reference / correct answer:

Argument construction

This argument features two versions/modes in which The World Tribune newspaper is available: the Print Mode and the newspaper's website (called the Web Mode henceforth).

Over the past 2 years:

The Print Mode's circulation has decreased by 40% - Premise 1 The Web Mode's traffic has increased by 30% - Premise 2

The website contains many news sections and blogs that are not featured in the print newspaper but are the most read pages of the website. This is Premise 3.

The Conclusion drawn (= the decision made) by the newspaper from these three premises is that:

to maintain profits, the newspaper should:

discontinue the still-profitable Print Mode introduce more exclusive content on the website that is similar to the most read pages of the website.

When we analyze the premises of this argument, we realize that from Premises 2 and 3, the decision-makers at the newspaper have assumed that the increase in the Web Mode's traffic is due to the exclusive content that makes for the website's most read pages. It is due to this assumption that they have decided to introduce more such content on the Web Mode. It can also be said that these decision-makers believe (assume) that because such content led to an increase in the website traffic in the past two years, introducing more such content will inevitably increase the website traffic in the future too. That is, they are assuming that a past relationship between two metrics (amount of exclusive content that forms the most-read pages of the Web Mode, website traffic) that held in the past will hold in the future too.

Further, the explicit goal of the newspaper is "to maintain its profits." However, the decision that it has taken concerns its reach – because the reach ("circulation") of the

Print Mode was decreasing while the reach ("traffic") of the Web Mode was increasing, the newspaper decided to kill the still-profitable Print Mode and focus solely on the Web Mode and take measures to increase the traffic of the Web Mode further. So, one necessary assumption that the decision-makers have made is that the increase in profits from increasing the traffic of the Web Mode will at least offset (if not exceed) the loss of profits due to closing down the Print Mode.

The decision-makers assume that this decision will enable them to "maintain profits," that is:

z ≥ x + y => z − y ≥ x

=> (Post-decision Increase in profit from Web-Mode) ≥ (Post-decision Loss of profit from Print-Mode)

Therefore, to sum up, the assumptions that have gone into the newspaper's decision are:

over the past two years, the increase in the Web Mode's traffic was due to the exclusive content that makes for the website's most read pages in the future too, introducing more such content will continue to drive an increase in the Web Mode's traffic (Post-decision Increase in profit from Web-Mode) ≥ (Post-decision Loss of profit from Print-Mode)

In analyzing the options in an assumption question, the Negation Test often comes in handy. Since a necessary assumption is, by definition, vital for the conclusion to be logically valid, we can test an answer choice by deeming it to be false. If, upon doing so, the conclusion no longer holds, this means that the answer choice in question is indeed a necessary assumption.

Let's analyze each option one by one.

Answer choices explanation

[The print circulation of the newspaper would not have declined further in the near future.] This option is incorrect. Suppose the print circulation of the newspaper would have declined further in the near future. Then, the perception that the Print Mode is a sinking business would be further strengthened and the newspaper's decision to kill the Print Mode would be validated. So, if we Negate this answer choice, the conclusion (= decision made by the newspaper) stands strengthened, instead of being demolished. Therefore, this answer choice fails the Negation Test.

[To access the content on the newspaper's website, the readers of the website will be willing …] This option is incorrect. Let the revenue that the print edition of the newspaper earned per reader each month (at the time of the decision) be dollars. Suppose the readers of the newspaper's website are not willing to pay a subscription fees of dollars per month for access to the website content. Does this necessarily mean that the newspaper will not be able to maintain its profits? No. For example, suppose the readers of the website are only willing to pay a monthly subscription fees of dollars. If the number of website readers is more than ten times the number of print-edition readers (which it very well might be, because, from the argument, we only know the percentage changes in readership of the print-edition and the website traffic, and not the actual numbers), then the revenue from the website subscription fees will be greater than the revenue from the print-edition. If the costs of the website are not greater than the costs of the print-edition, then the profits from the website will be greater than the profits that the print-edition earned at the time of the decision. Therefore, negating this answer choice does not necessarily impact the conclusion.

[The print circulation of the newspaper declined in the past two years…] This option is incorrect. Suppose the print circulation did not decline in the past two years because of the content offered in the Web Mode but due to some other reason. The facts of the case still remain the same – the print circulation was declining, the Web Mode traffic was increasing, and the newspaper wanted to maintain its profits. So, negating this answer choice has no impact whatsoever on the conclusion drawn.

[The revenue earned from increased website traffic will not be less than…] This option is incorrect. Suppose the revenue earned from increased website traffic is indeed less than the revenue lost by discontinuing the print edition. However, if the costs incurred by the newspaper for the Web Mode are far lesser than those for the Print Mode, then profits earned by the newspaper for the Web Mode can still be greater than or equal to the profits earned for the Print Mode. Therefore, the conclusion ("to maintain profits," kill the Print Mode and put more of XYZ type of traffic-increasing content on the Web Mode) can still stand. Therefore, this answer choice fails the Negation Test.

[Introducing more content similar to the exclusive content on the most …] This option is correct. Suppose that introducing more content similar to the exclusive content on the most read pages of the website will not increase the newspaper's website traffic further. The newspaper had assumed: (More such content --> More Web Traffic --> More Profit from Web-Mode that would at least offset the loss of profit from Print-mode). The negation of this answer choice breaks this chain of assumptions and therefore suggests that the newspaper's decision may not result in greater profit from Web-Mode that would at least offset the loss of profit from Print-Mode. Therefore, the profits of the newspaper may not be maintained. The negation of this answer choice substantially weakens the decision made by the newspaper. Therefore, this answer choice represents a necessary assumption on which this decision depends.

Reference / correct answer:

Argument construction

The argument starts with a premise – Premise 1: Astragalus linifolius (context-setting information: this is a rare plant species that is found only in the Colorado region of the United States) reproduces when a pollinating agent like a bee or a fly carries the pollen grain from the male part of a plant and deposits it onto the female part of another plant of the same species.

From this premise, it becomes clear that pollinating agents like bees and flies are necessary for the reproduction of Astragalus linifolius to take place.

Next comes the conclusion of the argument: To maintain the population of Astragalus linifolius (a rare legume species that is found only in the Colorado region of the United States), the use of pesticides that control grasshoppers should be banned in this region.

This conclusion is followed by two more premises:

Premise 2 - These pesticides result in significant mortality among the Bombylius flies.

Premise 3 - Bombylius flies are the most important pollinating agents of Astragalus linifolius.

Here is how these premises are used to draw the conclusion:

From Premise 1, we know that Astragalus linifolius cannot reproduce without pollinating agents. From Premise 3, we know that Bombylius flies are the most important pollinating agents of Astragalus linifolius. By combining Premises 1 and 3, we can draw a subsidiary conclusion that to conserve Astragalus linifolius, it's probably important to conserve Bombylius flies too. A decline in the numbers of the latter is likely to result in a decline in the numbers of the former.

When this subsidiary conclusion is combined with Premise 2, we draw the conclusion that to maintain the population of Astragalus linifolius, the use of pesticides that control grasshoppers should be banned in that region.

We are looking for the answer choice that provides additional information which makes this conclusion stronger than when the above two premises are used alone. Let us analyze the options one by one.

Answer choices explanation

[Astragalus linifolius has a short life-span.] This option is incorrect. This argument is concerned with the maintenance of population of a particular species. The population of a species would be maintained if its death rate and birth rate remain in equilibrium. The life-span of a species is irrelevant to the maintenance of its population and, therefore, to this argument.

[Astragalus linifolius is also pollinated, though to a much-lesser degree, by some local species of bees.] This option is incorrect. If there are other pollinating agents through which Astragalus linifolius can reproduce, then, assuming that these pollinating agents are not impacted by pesticides that control grasshoppers, this plant species might survive even if these pesticides are not banned. Therefore, this statement actually weakens the conclusion.

[The pesticides that control insect herbivores other than grasshoppers are even more toxic to Bombylius flies.] This option is incorrect. There may be pesticides that are more toxic to the Bombylius flies than the pesticides mentioned in the argument, but this does not strengthen the argument that to save Astragalus linifolius, the pesticides that control grasshoppers should be banned. For example, consider the statement 'to get better health, you should eat less sugar.' This statement is of the same format as the conclusion drawn in this argument: To achieve Goal A, do Action X. Does a statement that eating oily foods is even worse for your health than eating sugar strengthen the above example statement? It does not.

[Bombylius flies do not reproduce very fast and their populations ….] This option is correct. Suppose that Bombylius flies had been able to reproduce fast. Then, even if one spraying had significantly reduced the number of flies in a region from, say, 1000 to a mere 100, their fast breeding would have restored the population number to its pre-spraying level pretty soon and so there would probably not have been much adverse impact on the amount of pollination that these flies did for Astragalus linifolius and, therefore, in the population of this plant species. However, this statement tells us that the populations of Bombylius flies do not recover for many years post a pesticide spraying. In those years, therefore, the extent of reproduction of Astragalus linifolius is likely to decline, which in turn, is likely to decrease the population of this plant species.

[The populations of some other plant species in the Colorado region have decreased …] This option is incorrect. That other plant species have suffered greater declines than Astragalus linifolius since the spraying of pesticides that control grasshoppers started is irrelevant to the conclusion drawn for how the population of Astragalus linifolius may be maintained.

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Argument construction Premise 1:

In the 1920s, surveys of factory workers who painted watch dials with luminous paint (WDLP workers) found an alarming incidence of anemia, loss of teeth, bone fractures and death from cancer (HP = Health Problems). This premise tells us that 'WDLP workers' had 'HP.'

Premise 2:

This paint contained radium, a radioactive element.

WDLP would presumably have had many ingredients, one of which was radium – a radioactive element.

Subsidiary Conclusion drawn from Premises 1 and 2:

As a result, the industrial use of radioactive luminous paint was completely stopped by 1960.

The fact that this is a conclusion is suggested by the phrase 'as a result.' This conclusion also implies that those who had the power to decide what kind of paint was to be used on watch dials (the watch dial manufacturers, the government authorities etc.) assumed that 'WDLP workers' had 'HP' due to 'the radium in WDLP.'

Also note that Premise 1 was only concerned with WDLP workers. However, the subsidiary conclusion extends to all industrial use of LP. So, the decision-makers mentioned in the above paragraph also assumed that if radium caused HP in WDLP workers, then it would also cause HP in other industrial workers.

Premise 3:

However, radium stays active for hundreds of years.

So, the radium in the watches that were made before 1960 would still be active today, and, assuming the causal link between 'the radium in WDLP' and the 'HP of WDLP workers,' can cause HP even today.

Main Conclusion:

Therefore, those watch-collectors who own watches that have luminous dials and were made before 1960 should either bury these watches in the ground or store them in thick lead boxes to protect themselves and the people around them from anemia, loss of teeth, bone fractures and death from cancer.

The Main Conclusion makes use of some assumptions (unstated premises):

Burying a radioactive material in ground or storing it in thick lead boxes is enough to protect humans from it.

While Premise 1 presented an observation for WDLP workers, the main conclusion is drawn for watch-collectors. The author of the argument has assumed that what is true for WDLP workers would also be true for collectors of the watches made by these workers. This is a questionable extrapolation, as it might be expected that a

worker who painted watch dials with WDLP day-in and day-out would have had a much higher exposure to radium than a watch-collector who only looks at his watchcollection occasionally and for only a few minutes per watch at a time.

The Main Conclusion applies to a group of people (watch-collectors) in the present-time and the reason why watches made decades ago are still thought to pose a health hazard today is given in Premise 3, which states that radium stays active for hundreds of years. The main conclusion therefore depends on the assumption that it was the radium in the LP that caused the HP of WDLP workers. This assumption need not be correct. LP would have had many ingredients, one of which was Radium; no direct evidence is presented in the argument to indicate that it was Radium and not another ingredient of the LP that caused the HP of WDLP workers.

Note that this is a Strengthen-Except question (If one option 'least' strengthens the argument, it follows that the other four options strengthen the argument). We are looking for the one answer choice that does not strengthen the argument.

Let us analyze the options one by one.

Answer choices explanation

[The surveys also found that the incidence of anemia, loss of teeth, bone fractures and death from cancer ...] This option is incorrect. The group of workers mentioned in this option statement are the opposite of WDLP. These people did not use LP and, as per this option statement, they had no HP; the incidence of diseases mentioned in the argument among this group was the same as in the general population. So, 'the WD painters who used LP' had HP while 'the WD painters who did not use LP' did not have HP. This option statement strengthens the assumption that it was the LP that caused the HP in WDLP workers.

[The surveys also found that factory workers who painted watch dials with luminous paint, the extent of their ...] This option is incorrect. The more LP that a WDLP worker was exposed to, the more HP he had. The less LP that a WDLP worker was exposed to, the less HP he had. This clearly strengthens the assumption that it was the LP that caused the HP in WDLP workers.

[Barriers of lead or earth provide adequate protection to human beings from harmful radioactive substances.] This option is incorrect. This statement strengthens the main conclusion by validating an assumption on which it depends.

[People who wear watches that have luminous dials and were made before 1960 for more than a decade have an alarming incidence of anemia.] This option is incorrect. This statement strengthens the main conclusion by providing evidence that under certain circumstances (when the antique watches are worn for more than a decade), watch-collectors too can suffer from at least some of the HP (anemia) that the WDLP workers of Premise 1 suffered from. Thus, this option statement validates an assumption on which the main conclusion depends.

[Most chemists and laboratory workers who worked with radium for more than a year in the first decade…] This option is correct. This statement weakens the main conclusion because it provides evidence that there is a group of people who handled radium but who did not have HP. This suggests that an assumption on which the Main Conclusion depends - that the HP of the WPLD were caused by the radium in the LP – is probably incorrect.