Suppose lawyer of a particular ethnic group were favored in appointing judges, regardless of their ability. Would this result in judges from that ethnic group having lower IQ?
My first thought was: Yes– as a matter of mathematical necessity. But that is not correct. Indeed, I’ve published to the contrary.
“Lowering the Bar to Raise Up the Bar: Licensing Difficulty and Attorney Quality in Japan,” with J. Mark Ramseyer. Journal of Japanese Studies, 41(1): 113-142 (2015). Under certain circumstance, a relaxation in occupational licensing standards can increase the quality of those who enter the industry. The effect turns on the opportunity costs of preparing for the licensing examination: making the test easier can increase the quality of those passing if it lowers the opportunity costs enough to increase the number of those willing to go to the trouble of taking the test. We explore the theoretical circumstances under which this can occur and the actual effect of the relaxation of the difficulty of the bar exam in Japan from 1992 to 2011. http://rasmusen.org/papers/barpass-ram-ras.pdf.
Opportunity cost is one reason. A more general and purely mathematical one is related to option theory and the difference between marginal and average ability. If the favored group of lawyers has higher average ability, and we choose as judges those above threshold X, the same as other groups, then if we reduce the threshold slightly for that group, the worst judge in that group will be worse than the worst judge from any other group, but the average will still be higher. Indeed, the median will still be higher too.