Some people are peculiar in the sense that they are less interested in the advancement of knowledge than in practical matters. Massive IQ gains over time have practical relevance because they expose mistakes in measuring IQ. These mistakes are costly because they deceive us about causes and even deceive us into putting people to death who ought to be exempt. The root cause of all of these unfortunate consequences is scoring against “obsolete norms.”

Obsolete norms

An IQ score is only as valid as the test the person takes, and the test is only as valid as the standardization sample on which it is normed. When someone is assigned an IQ of 100 that means that their performance on a particular test was exactly average or at the 50th percentile. And the score is accurate only if the person is being compared to a representative sample of his or her peers, for example, a representative sample of American 14-year-olds tested at exactly the same time. The reason the test must have been normed recently is the existence of massive IQ gains over time.