Inflation is a scourge, so you take notice whenever someone tells you they would like to see a little more of it.

The Bank of Japan (BOJ), which has been seeking every reason imaginable to end its policy of near-zero interest rates, produced a study in May 2007 titled "The Costs And Benefits of Inflation: Evaluation For Japan’s Economy." The study is 63 pages long, filled with quantitative macroeconomics and attempts to find the "optimal inflation rate" for Japan, which the BOJ concludes are annual consumer price increases between 0.5 and 1.0 percent.

Why does the BOJ consider some inflation to be better than no inflation, or better than the deflation Japan has experienced over much of the past decade?