Claude S. Fischer in Boston Review:
Some observers respond to questions raised by the Flynn Effect by dismissing intelligence testing as an exercise in cultural domination. This ostrich-like response ignores the fact that IQ scores, whatever they measure, consistently correlate with important outcomes such as how well people perform their jobs and how long they live. Such dismissal also ignores the growing evidence that there is a physical, neurological basis to cognition and cognitive skills.
A more serious critique of the research attacks the definition of intelligence. Researchers in the intelligence field define it as a general capability to reason, understand complex ideas, think abstractly, and solve problems. You can measure it, they argue, using IQ tests. Critics consider these tests to be superficial and argue that they ignore other kinds of intelligence such as emotional intelligence or deeper traits such as wisdom. While researchers cannot track historical trends in wisdom, they are trying to wise up about the apparent historical increase in IQ.
One might suspect that the tests have gotten easier. They haven’t. In fact, the tests have gotten harder in order to keep the average IQ at one hundred. By reversing that process, Flynn showed the long-term rise in real performance.
Other challengers argue that we are not really smarter than our great-grandparents; it’s just that people today learn the answers to test questions in school or have become familiar with testing. However, scores on the parts of tests that are most easily taught and are the most culture-laden—say, recognizing vocabulary or knowing geography—have not changed much. Scores on those parts of tests that measure the most abstract, presumably culture-free thinking—say, drawing logical inferences from patterns in designs—have risen the most. The sorts of thinking that are supposedly most detached from classroom and cultural learning are the ones that have really improved.
So if a real increase in some kind of cognitive ability is under way, the question is why.