The Globe and Mail reports in its Thursday, May 16, edition that the argument against extremely low interest rates tends to be reduced to concerns about inflation and asset-price bubbles, but there are other reasons to worry. The Globe's Kevin Carmichael writes that C.D. Howe Institute economist Paul Masson says: "The cumulative effect of artificially low interest rates will show up in pervasive distortions of economic decisions. ... The Bank of Canada should start now to reverse some of the monetary stimulus and begin raising interest rates." Dr. Masson's call for higher rates is a challenge to the debate over Canada's monetary policy. Like the central bank, Dr. Masson worries that too many households will be unable to keep up with their debt when borrowing costs inevitably rise. Dr. Masson also sees the potential for trouble in the insurance industry. These companies offset their liabilities with investment income, traditionally done by purchasing government bonds. Because yields are so low, profit margins are shrinking -- creating an incentive to purchase riskier assets. The rush to dividend-paying stocks could be hurting small companies, which typically reinvest their earnings.