The fact that education has little or no effect on IQ happens to be true, but it's not guaranteed by definition or design. I.e., it's logically possible (and, in fact, popularly believed) that education makes your brain work better in general, and that learning French will improve your chess rating and your grades in calculus class. It was discovered that education doesn't help general intelligence much through tests designed on more fundamental principles like elimination of group factors and improving test-retest reliability.