Question

Since 1978 when the copyright law was changed, books that are less than fifty years old must not be photocopied without the publisher’s permission. Thus, any book that has been photocopied since 1978 without the publisher’s permission must be at least fifty years old.

The reasoning above exhibits a flaw similar to one in which of the following?

Option A
Option B
Option C
Option D
Option E

(This question is from Official Guide. Therefore, because of copyrights, the complete question cannot be copied here. The question can be accessed at GMAT Club)

Solution

The Story

Since 1978 when the copyright law was changed, books that are less than fifty years old must not be photocopied without the publisher’s permission.

In 1978 the copyright law was changed. Since then, books less than fifty years old may only be photocopied with the publisher’s permission. 

Thus, any book that has been photocopied since 1978 without the publisher’s permission must be at least fifty years old

The author concludes that since the revised copyright law came into existence, the only books that have been photocopied must have been at least fifty years old.

Gist: 

The modified copyright law restricts photocopying of recent books. Thus any books photocopied since the law change must not have been recent or the copiers must have got the publisher’s permission.

The Gap

Just ‘cause a law has been passed does not necessarily mean that everyone will follow it. The author, though, assumes that everyone follows the law and the only books that have been photocopied either were older than fifty years or were copied with the publisher’s permission.

Clearly the author has not come across Indian students 🙂

The Goal

The basic flaw in the reasoning, as discussed above, is that the author assumes no one has broken the modified copyright law since it came into existence. We need to find an argument that has a similar flaw in reasoning.

The Evaluation

(A) Incorrect. This is a logical argument. Since any member must be a planet or a moon, if an asteroid is neither, it will not be a member. Since there is no flaw in the argument, this argument is not parallel to the one discussed above.

This is the first thing we recommend you do in a parallel argument question. Typically in such questions, the argument presented on top will have a flaw in reasoning. So, while going through the options, the first question to answer after understanding each option is: Is there even a flaw? If there isn’t one, we do not even need to bother figuring out whether the argument is parallel. A logical argument cannot be parallel to a flawed argument in terms of reasoning.

(B) Incorrect. There is a flaw in this argument. The argument confuses a necessary condition (buying a bus pass to ride a city bus) for a sufficient condition. A bus pass is mandatory for riding a city bus. However, having a bus pass does not imply that someone must be riding a bus. One could very well have a bus pass and be sitting at home. While this argument is flawed, the flaw in reasoning is not similar to the flaw in the argument above. The argument on top is about the certainty of compliance just ‘cause there is a law. This one is about confusing a necessary condition for a sufficient one.

C) Correct. This argument makes the assumption that all drivers must be following the right turn signal rule. So, if a driver did not signal, it could not mean that he could have broken the rule and turned right without a signal; it must mean that the driver did not turn. This assumption is logically identical to the one made in the above argument. Both these arguments confuse the existence of a rule with conformity with the rule.

Here’s another parallel example: If you earn money above a minimum amount, you must pay taxes. So, anyone who did not pay taxes must not have earned money above that minimum amount.

Clearly, the author does not know of tax evasion.

(D) Incorrect. The option does not say that anyone who does not have a passport cannot cross a national boundary. It says that someone like that cannot ‘legally’ cross a national boundary. That is actually logical. This is a logical argument. So as discussed in option A, since there is no flaw in the argument, this argument is not parallel to the one given in the passage.

Food for thought: What if we were to remove the word “legally” from this option? Anyone who legally crosses a national boundary must have a passport; thus anyone who does not have a passport cannot legally cross a national boundary. Is there a flaw in this reasoning? If so, is it similar to the one in the passage?

(E) Incorrect. This option also confuses a necessary condition for a sufficient one. It is necessary for wage earners in the state to pay state taxes. Doesn’t mean they are the only ones who pay state taxes. There could be other states as well that require their wage-earning residents to pay state taxes. This option is also flawed. However, the flaw is similar to the one we saw in option B, and not similar to the flaw we observe in the copyright law argument.

This solution was created by Anish Passi and Chiranjeev Singh.

If you have any doubts regarding any part of this solution, please feel free to ask in the comments section.

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