Integrity, understood as a disposition to behave in prosocial, ethical, and principled ways rather than corrupt or self-serving ones, is among the strongest and most consistent predictors of job performance and leadership effectiveness. The reason is far from mysterious. Leadership, whatever its context, is a collective enterprise. No meaningful goal, from building empires to running companies, has ever been achieved alone.

Across history, not just in humans but also other animals, cooperation has depended less on raw power than on trust. Ancient trading societies flourished precisely because reputation constrained behavior: Merchants in Phoenician city-states, medieval guilds, and Silk Road networks relied on repeated interactions and informal enforcement mechanisms to ensure that partners honored their commitments. Those who cheated were excluded, not merely judged. Trust, in effect, functioned as an early mechanism for coordination and enforcement.

The same logic applies in modern organizations. Teams perform........

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