Is There a Stock Bubble? Joining the NYT Debate

Since the NYT decided to devote a Room for Debate on the question of whether the stock market is currently in a bubble, I thought I should join the party as one of the stock bubble warners from the 1990s. To my mind the story for the overall stock market is a fairly simple one. Look at the ratio of stock prices to trend earnings.

This one doesn't look too terrifying. Obviously the market is hitting record highs measured in nominal dollars, but if we expect the price to earnings ratio to remai...