The point is that the supply-siders were absolutely sure that his policies would produce disaster

It should go without saying that the supply-side idea—which is that tax cuts have such a positive effect on the economy that one need not worry about paying for them with spending cuts—does not persist because of any actual evidence in its favor. If you want, any nonpartisan economist can explain to you at length what really happened during the Reagan years, and why you can’t seriously claim his record as an advertisement for supply-side policies. But surely it is enough to look at the extraordinary recent record of the supply-siders as economic forecasters. In 1993, after the Clinton administration had pushed through an increase in taxes on upper-income families, the very same people who have persuaded Dole to run on a tax-cut platform were very sure about what would happen. Newt Gingrich confidently predicted a severe recession. Articles in Forbes magazine urged readers to get out of the stock market to avoid the inevitable crash. The Wall Street Journal editorial page had no doubts that the tax increase would sharply increase the deficit instead of reducing it. Well here we are, three years later: The economy has created 10 million new jobs, the market is up by 1500 points, and the deficit has been cut in half. I’m not saying that Clinton’s policies led to that result—they account for only part of the good news about the deficit, and hardly any of the rest. But the point is that the supply-siders were absolutely sure that his policies would produce disaster—and indeed, if their doctrine had any truth to it, they would have.

Supply-Side Virus Strikes Again - By Paul Krugman - Slate Magazine

15 Years later and the debate still rages on, facts be damned.