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Uncharacteristic Sample |
| Description: | ||
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| The argument draws a conclusion from cases that are not sufficiently diverse to give a fair representation of the class about which a conclusion is being drawn. | ||
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| Comments: | ||
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| Be careful not to confuse this fallacy with Hasty Generalization. A sample may be quite large, but still be unrepresentative of the whole. | ||
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| Examples: | ||
| "Judging by the opinions of people who call into talk shows, most Americans believe that the F.B.I. is a bunch of jack-booted thugs." | ||
| "American cars are built to last. In a sample of American-made automobiles driven in San Diego, we found that most of them showed little corrosion or weathering, even if they had been on the road for over ten years." | ||
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| Discussion: | ||
| Diversity in a sample is actually a much more important characteristic than mere size. A small sample can be quite accurate, if it is as diverse as the class it is called upon to represent. For example, in order to determine whether a bunch of grapes has seeds or not, it is usually enough to sample just one grape. On the other hand, a sample can be very large yet still be inaccurate if it is uncharacteristic. In the example above, the sample of automobiles in San Diego might involve hundreds, or even thousands of cars, yet still be likely to lead to a false conclusion, since cars in San Diego are subject to much less weathering than the general population of cars. | ||
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| Classification: An Error in Sampling (an inductive fallacy of soundness with a falsehood in the minor premiss). | ||
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| Source: I first became aware of this fallacy from W. Ward Fearnside and William B. Holther, Fallacy: the Counterfeit of Argument (1959). Fearnside and Holther describe the fallacy, but name it "Unrepresentative Generalization." I coined the term "Uncharacteristic Sample," which I consider to be a better description of the fallacy. I doubt that Fearnside and Holther's book is the earliest source for this fallacy, but I have not so far been able to authoritatively identify an earlier source. Please contact me if you can point me to a potentially useful clue regarding the original source of this fallacy. | ||
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