Valuations continue to reach new highs, and the market looks very expensive—by some measures, the third highest of all time after 1929 and 1999. Meanwhile, the economy is showing signs of slowing. I have made my own views about what might come next pretty clear, but it’s worth taking the counterarguments—that current stock prices are reasonable, not a cause for concern—seriously as well. I say this all the more because analysts I respect are increasingly positing that it is different this time. So let’s see if we can make a case for that.