To put that in perspective, consider that the enormously profitable and near-monopoly Microsoft Corp. trades at 66 times earnings. Unfortunately, their argument is no more convincing as a book than it was as an article. The problem with their thesis is that to arrive at Dow 36,000, you have to accept their proposition that stocks are no riskier than bonds. And that flies in the face of what economists and B-School finance professors have been saying for decades. It also runs counter to what we observe in the market every trading day.
Stocks are risky.
The argument also runs counter to what we know about corporate finance. Stockholders only get paid, with earnings and perhaps dividends, if there's anything left over. In other words, bondholders have a far higher probability of getting paid. They know both the amount they will get paid and when payments will come. A stockholder may ultimately reap riches, but the timing is anything but certain.