Self-study
A spy fails by being caught, and it is normally only through being caught that spies reveal their methods. The successful spy is never caught. So the available data are skewed: One can learn a lot about what makes a spy fail but very little about what makes a spy succeed.
23.
Which one of the following arguments is most similar in its reasoning to the argument above?
a
Of those who participated in the marathon, some succeeded and others failed. But those who did not participate at all neither succeeded nor failed, since both success and failure require participation.
Mismatched conclusion. (A) divides a group (marathon runners) into two subgroups (those who succeeded and those who failed), before concluding that those who do not fall into the main group also don’t fall into either subgroup. The conclusion, however, concludes that the data over a group are biased because there is only data from one of its subgroups, so (A) doesn’t match.
b
People who are aware of their motives can articulate them. But unconscious motives are usually impossible to acknowledge. So people are more likely to hear about other people's conscious motives than their unconscious ones.
The argument proceeds by claiming that there is incomplete information about a group (motives). This is because the group can be divided into two subgroups (conscious and unconscious motives), and most of the information is only about one of the subgroups (conscious motives).
c
It is unclear whether the company’s venture succeeded, because the criteria for its success are undefined. But if the venture had had a measurable goal, then it would have been possible to judge its success.
Mismatched premises and conclusion. (C) tells us that it is difficult to evaluate the success of something because there are no measurable criteria. It then reaches the conditional conclusion that, if there were measurable criteria, then we could evaluate success. The stimulus, however, does not have a conditional conclusion, and instead tells us that the data over a group is incomplete.
d
A teacher is someone who teaches. In addition, there are people who teach but are not called teachers. So while the number of those called teachers is large, the number of those who teach is even larger.
Mismatched premises and conclusion. (D) presents a conditional relationship (if you’re a teacher, then you teach). It then tells us that some people satisfy the necessary condition but not the sufficient condition to validly conclude that more people satisfy the necessary condition than the sufficient condition. The stimulus, however, divides a group into two subgroups before concluding that the data on the group is incomplete, so (D) doesn’t match.
e
Because someone intervened in the conflict, the effects of that intervention can be discerned. But since no one can investigate what does not happen, it is impossible to discern what would have happened had someone not intervened.
Mismatched premises and conclusion. (E) presents an event (an intervention in a conflict) and tells us that information on this event can be gathered because it occurred. It then concludes that information on what would have happened had the event not occurred cannot be gathered. The stimulus does not attempt to prove that information cannot be gathered, however, and instead concludes that information on a certain group is incomplete, so (E) doesn’t match.