There were two by Bank of Japan managers in the Wall Street Journal lede regarding the BoJ’s interest rate moves.

A week after Japan’s top central banker shook up global markets with comments about raising interest rates, one of his deputies walked them back Wednesday and promised not to raise rates when markets are unstable.

The lesser of the two foolishnesses is that walkback of the BoJ’s statement that it was about to raise interest rates. The increase was both correct and necessary sooner rather than later. The deputy never should have been authorized to walk that commitment back. The BoJ simply should have stopped talking about the raise, having said it was coming. It should have simply done the raise at the appointed time.

The larger foolishness, though, was that subsequent commitment. It’s a promise that no one in the BoJ has any hope of keeping, or the BoJ will never raise interest rates. Stock markets are always unstable.

The stock market’s equilibria—moving sideways for a time—are unstable; it takes no particular event or perceived event to bump the market into a rise or a drop. Rises in the market are not stable; it takes no particular event or perceived event to bump the market into a short- or intermediate- or long-term fall—or into another supposedly stable sideways move. Falls in the market are not stable; it takes no particular event or perceived event to bump the market into a short- or intermediate- or long-term rise—or into another supposedly stable sideways move.

Timing the market is a money losing move; even when central bankers try it. All timing does is mitigate losses, at the expense of long-term gain, but even that presupposes some measure of stability. Long-term gain sacrifice as the price to pay for mitigating losses often is useful for those individuals who must preserve the wealth they have—they’re retired, for instance, and have no other income—but sacrificing long-term gain is a bad move for a nation, whose citizens need long-term growth for the sake of their own and future generations.

If central banks want market stability, such as may be available within a band of inflation around a target rate, they must generate that more-or-less availability by setting their nation’s interest rates at levels historically consistent with their nation’s inflation goals and then leave those rates alone and live with the natural volatility of a free market.