Banks continue to lobby for weaker financial regulation: capital requirements are excessive, liquidity requirements are overly restrictive, and stress tests are too burdensome. Yes, in the aftermath of the 2007-09 financial crisis, we needed reforms, they say, but Basel III and Dodd-Frank have gone too far.

Unfortunately, these complaints are finding sympathetic ears in a variety of places. U.S. authorities are considering changes that would water down existing standards. In Europe, news is not promising either. These developments are not only discouraging, but they are self-defeating. Higher capital clearly improves resilience. And, at current levels of capitalization, it does not limit banks’ ability to support economic activity.

As it turns out, on this particular subject, there may be less of a discrepancy between private and social interests than is commonly believed. The reason is that investors reward banks in jurisdictions where regulators and supervisors promote social welfare through tougher capital standards....