True, but almost a tautology: IQ tests are designed to be a metric of intelligence that is stable over time. They indeed have that property. Other correlates of

True, but almost a tautology: IQ tests are designed to be a metric of intelligence that is stable over time. They indeed have that property. Other correlates of intelligence are less stable. The everyday things by which one's intelligence is judged, like ability in tasks, can clearly be increased.