The impotence of monetary policy

This post by Krugman sums it up. It's a pity things are even worse than he suspects:

A problem with the current BOJ policy, however, is its vagueness. What precisely is meant by the phrase “until deflationary concerns
subside”? Krugman (1999) and others have suggested that the BOJ quantify its objectives by announcing an inflation target, and further that it be a fairly high target. I agree that this approach would be helpful, in that it would give private decision-makers more information about the objectives of monetary policy. In particular, a target in the 3-4% range for inflation, to be maintained for a number of years, would confirm not only that the BOJ is intent on moving safely away from a deflationary regime, but also that it intends to make up some of the “price-level gap” created by eight years of zero or negative inflation.

…

BOJ officials have strongly resisted the suggestion of installing an explicit inflation target. Their often-stated concern is that announcing a target that they are not sure they know how to achieve will endanger the Bank’s credibility; and they have expressed
skepticism that simple announcements can have any effects on expectations.

OK, so say the BOJ or Fed announce a higher inflation target. Now what? Inflation means higher price levels, and for a price, you need a transaction. Announcing a target does not create a transaction, and therefore, does not influence a price. The BOJ's concerns that their credibility is on the line are right on -- the standard monetary mechanism (overnight interbank interest rates) has no impact on prices.

Unconventional monetary mechanisms, like changing other rates, have no impacts for the same reason. The only thing that has impact are transactions, a transfer of nominal assets from the Govt to the non-Govt sector. And this is fiscal policy, not monetary policy.