Instead of asking what IQ measures I think it's probably more useful to simply ask what it predicts. Often discussions regarding IQ seem to get bogged down in

Instead of asking what IQ measures I think it's probably more useful to simply ask what it predicts. Often discussions regarding IQ seem to get bogged down in debates around the definition and value of intelligence, or the ability of an IQ test to accurately measure it. But whatever your opinion on what IQ tests are measuring, IQ has undoubtably been shown to have a high statistical predictability for many of the positive (and negative) life outcomes we're interested in as a society. For example, if you score higher on an IQ test you're statistically much less likely to go to prison and much more likely to have a higher income. Personally I think IQ is something worth thinking about in the context of group behaviour and performance. For example, at the level of a nation it's worth measuring mean IQ and being concerned about any persistant annual declines in IQ, or simply to understand why some cohorts might have significantly higher or lower IQs. On the level of the individual I'd question how useful it is.