Morck and Yeung take the (perhaps surprising, almost Misesian) position that “[i]nstrumental variables can lose value with repeated use because of an econometric tragedy of the commons: each successful use of an instrument creates an additional latent variable problem for all other uses of that instrument,” and that “[e]conomists should therefore”consider historians’ approach to inferring causality from detailed context, the plausibility of alternative narratives, external consistency, and recognition that free will makes human decisions intrinsically exogenous.”

Mahmood Arai