Too many humilities: Construct proliferation and the measurement of a consequential trait

Humility is among the most morally and socially consequential traits in individual-differences research, yet it is measured by more than 20 instruments spread across four traditions that differ in theoretical level and have developed largely on separate tracks: intellectual, relational, and cultural humility, and the Honesty-Humility factor of HEXACO. Two recent papers bring the costs of this fragmentation into focus. Costello et al. (2023) report that widely used intellectual humility self-reports track confidence more than error recognition, a failure of criterion-related validity against metacognitive calibration and error recognition. Pärnamets et al. (2026) show that consolidating measures within a tradition is feasible and clarifying. We argue that cross-tradition integration should become a priority for individual-differences science, and we outline what it requires: multitrait-multimethod designs; comparison of correlated-factor, higher-order, and bifactor models; attention to discriminant and incremental validity, and to measurement invariance; and validation against distinct classes of external criteria that have psychometric support of their own.