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Generalization: Inductive Reasoning

Generalization and analogy, which we consider in the next section, are the main tools by which we accumulate knowledge and analyze our world. Many people define generalization as “inductive reasoning.” In colloquial speech, the phrase “to generalize” carries a negative connotation. To argue by generalization, however, is neither inherently good nor bad. The relative validity of a generalization depends on both the context of the argument and the likelihood that its conclusion is true. Polling organizations make predictions by generalizing information from a small sample of the population, which hopefully represents the general population. The soundness of their predictions (arguments) depends on how representative the sample is and on its size. Clearly, the less comprehensive a conclusion is the more likely it is to be true.



During the late seventies when Japan was rapidly expanding its share of the American auto market, GM surveyed owners of GM cars and asked them whether they would be more willing to buy a large, powerful car or a small, economical car. Seventy percent of those who responded said that they would prefer a large car. On the basis of this survey, GM decided to continue building large cars. Yet during the ‘80s, GM lost even more of the market to the Japanese.


Which one of the following, if it were determined to be true, would best explain this discrepancy.

  1. Only 10 percent of those who were polled replied.
  2. Ford which conducted a similar survey with similar results continued to build large cars and also lost more of their market to the Japanese.
  3. The surveyed owners who preferred big cars also preferred big homes.
  4. GM determined that it would be more profitable to make big cars.
  5. Eighty percent of the owners who wanted big cars and only 40 percent of the owners who wanted small cars replied to the survey.

The argument generalizes from the survey to the general car-buying population, so the reliability of the projection depends on how representative the sample is.
At first glance, choice (A) seems rather good, because 10 percent does not seem large enough. However, political opinion polls are typically based on only .001 percent of the population. More importantly, we don’t know what percentage of GM car owners received the survey.
Choice (B) simply states that Ford made the same mistake that GM did.
Choice (C) is irrelevant.
Choice (D), rather than explaining the discrepancy, gives even more reason for GM to continue making large cars.
Finally, choice (E) points out that part of the survey did not represent the entire public, so (E) is the answer.


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