>If you don't think lowering interest rates causes the value of money to go down, ask what would happen if the central bank set the interest rate to negative 10%.

Lowering the interest rate below zero means that QE becomes irrelevant and that the central bank should undo all of it. Afterwards the central bank should raise the minimum reserve requirements above 50% and tighten its money supply as much as feasible. As holders of bank balances want to avoid negative interest fees, they will choose to invest in certificate of deposit accounts. The original borrowers now have an incentive to refinance their debts with this source and repay the money creating loans they have gotten from their banks which ultimately reduces the circulating money supply. If lenders refuse to accept a -10% return and instead lend at the rate of inflation, then borrowers will know when to stop without the government or central bank telling them to restrain themselves.