The fallacy of hasty generalization occurs when a generalization is formed on the basis of an unrepresentative sample. As we may already know, to be accurate, a generalization about a group should be based upon a sample that reflects the diversity of that group. One way of ensuring a representative sample, in some cases, is to select as large a sample as possible. The more people polled, for example, the more likely it is that the results truly represent the group. However, an accurate generalization does not necessarily require a large sample. In Gallup opinion polls, generalizations are typically based on surveys of a very small number of people. However, the pollsters are careful to select a typical or representative group of people for their sample. Let us consider the following examples below.
Example 1
I have surveyed twenty-five students―each from a different campus organization―out of a student body of two thousand, and all of them prefer to use the activity fund for a film series. So, probably the majority of all students would prefer a film series.
Example 2
I have spoken to the members of the campus Glee Club, and they prefer to use the activity fund for a film series on birds. So, probably a majority of the two thousand students would prefer a film series on birds.
As we can see, the arguer in the first example forms a generalization about the preferences of two thousand students on the basis of a sample drawn from various campus groups. It is, therefore, reasonable to assume that this sample accurately reflects the diversity of opinion among the students. Thus, this generalization does not commit the fallacy of hasty generalization.
However, in the second example, the generalization is based solely upon a survey of one, rather select group, the members of the Glee Club. Although their preferences should be considered, it is not likely that their group is representative of the student body as a whole; neither is it a random sample of opinions. Hence, the generalization rests on an unrepresentative sample.
Let us consider another example. Columnist Ann Landers conducted an informal survey in which she asked her women readers to reply to this question: “Would you be content to be held close and treated tenderly and forget about “the act”? She reports that 100, 000 women responded, with 72 percent answering yes. Among the conclusions:
Example 3
The most surprising aspect of this survey was that 40 percent of the yes votes were from women under forty years of age. What does this say about the sexual revolution? It says, in the boudoir at least, it has been an abysmal failure.
Landers reports that 72, 000 women answered yes and that of that group, 42 percent, or 28, 800, were under forty years of age. She concludes that the sexual revolution “has been an abysmal failure” on the basis of the 28, 800 women under age forty who answered yes. Setting aside the problems with the survey questions itself and, in particular, the meaning of a yes answer, can we say that her sample of 28, 800 women is large enough to support a generalization about a majority of the nation’s approximately 2 million women under the age forty years? Although it is a significant sample, we may wonder whether it is indeed representative of the nation’s women under forty. Landers provide no further information about the makeup of the sample. We know only that it is composed of women forty years or under who read the survey and responded. Lacking such information we cannot conclude that is an accurate generalization, and we may suspect the fallacy of hasty generalization.
To identify the fallacy of hasty generalization, we need to look for a conclusion that generalizes over a group, and notice whether the basis for the generalization is both representative of the group and sufficiently large to justify the generalization; otherwise, a fallacy of hasty generalization may have been committed.