The Dow Jones industrial average flirting with an all-time high is just one more signal of how healthy the Bush administration’s tax cuts have been for the American economy. The stock market has withstood a war in Iraq, an untested new chairman of the Federal Reserve Bank who is filling the large shoes of Alan Greenspan, high oil prices, the Sarbanes-Oxley Full Employment for Accountants Act, and Eliot Spitzer’s raid on the New York Stock Exchange and many of its brokerage houses. Yes, the stock market reached new highs in the Clinton years, but those valuations were unsustainable, driven partly by speculation in money-losing Internet companies. In this market, stock prices are backed by underlying earnings — that is, actual profits — that have been robust, driven by American ingenuity, freer global trade, and yes, the incentives unleashed by those Bush tax cuts. Experience shows that economic upturns don’t last forever, but this one has been remarkably durable and long-lived, especially given the background conditions. It’s something to celebrate as the third quarter ends.