The establishment of the Fed in 1913 as a lender of last resort that would temporarily replace the cash withdrawn by fleeing depositors was an important advance toward banking stability. But although the Fed could ameliorate the consequences of panics, it couldn’t prevent them. The system wasn’t stabilized until the 1930s, when the government separated commercial banking from investment banking, tightened bank regulation and created deposit insurance. This system of rules virtually eliminated bank runs and bank failures for decades, but much of it was junked in a deregulatory process that culminated in 1999 with the repeal of the 1933 Glass-Steagall Act.

The Federal Deposit Insurance Corporation now covers balances up to a $250,000 limit, but this does nothing to reassure large depositors, whose withdrawals could cause the system to collapse.

In fact, an overwhelming proportion of the “quick cash” in the global financial system is uninsured and prone to manic-depressive behavior, swinging unpredictably from thoughtless yield-chasing to extreme risk aversion. Much of this flighty cash finds its way into banks through lightly regulated vehicles like certificates of deposits or repurchase agreements. Money market funds, like banks, are a repository for cash, but are uninsured and largely unexamined.

Relying on the Fed and other central banks to counter panics is dangerous brinkmanship. A lender of last resort ought not to be a first line of defense. Rather, we need to take away the reason for any depositor to fear losing money through an explicit, comprehensive government guarantee. The government stands behind all paper currency regardless of whose wallet, till or safe it sits in. Why not also make all short-term deposits, which function much like currency, the explicit liability of the government?

Guaranteeing all bank accounts would pave the way for reinstating interest-rate caps, ending the competition for fickle yield-chasers that helps set off credit booms and busts. (Banks vie with one another to attract wholesale depositors by paying higher rates, and are then impelled to take greater risks to be able to pay the higher rates.) Stringent limits on the activities of banks would be even more crucial. If people thought that losses were likely to be unbearable, guarantees would be useless.