Nominal interest rates are artificial. Real interest rates (nominal rates - inflation) are not. If central banks set nominal interest rates too low you get in

Nominal interest rates are artificial. Real interest rates (nominal rates - inflation) are not. If central banks set nominal interest rates too low you get inflation which negates the purchasing power of the borrowed money. That's what the grandparent poster was alluding to. (The mathematical model - and the proof - for this is taught in most introductory macroeconomics courses. So is monetarism, which is the "declining rates = stimulus" that you mention.) It's been a persistent question why the super-low nominal interest rates that central banks have set for the last decade haven't resulted in consumer inflation, and there's no consensus among experts for it. My personal theory is that it comes from the entry of China and other large developing nations into the world economy, which a.) has dramatically lowered the price of labor-intensive consumer manufacturing, offsetting much of the inflation caused by the large money supply and b.) changed the mix of savers in the world economy; Chinese people are much more in the habit of saving large fractions of their income than Americans are, which leads to a glut of savings, which lowers the real interest rate.