Will the curtain stay up on Reaganomics?

In the 1980 presidential race John Anderson kept asking Ronald Reagan, how is it possible to raise defense spending, cut income taxes, and balance the budget all at the same time? Easy, said Mr. Reagan. It can be done by using supply-side economics - the ''Kemp-Roth'' program. Taxes are already too high, and if they are cut appropriately the federal revenues will increase not diminish. Simple. And Mr. Reagan, aided by his nimble-minded, razor-sharp, 36-year old budget director, David Stockman, launched the tax-cut program; there would be a dramatic across-the-board, three-year slash in income taxes, a cut in federal expenditures, except defense, and tight monetary controls. In brilliant political victories he set the stage in Congress. Surely after that investors would take over! They would see that a new era is dawning. There would be robust growth in production; stocks and bonds would appreciate. Competition would reduce prices. Bigger profits would swell Treasury coffers. Tight money rates would bring down inflation. Gloom would go.

Some of that has happened, but only a little. Interest rates are down and inflation isn't so high as it was. But Mr. Reagan announces that we are now in a recession. A lot of other economic arrows point down, like employment. Nobody knows how big the deficit will be this year that Mr. Reagan thought he was cutting. As to next year the deficit may be horrendous. Mr. Reagan will have to start preparing his new budget message for January shortly - assisted, I presume , by budget director David Stockman. It should be an interesting document.

In the meantime we have got one of the most revealing inside political documents of modern times, the month-by-month comments of young Mr. Stockman to William Greider of the Washington Post, condensed in the December issue of the Atlantic Monthly.

Primarily this reveals that even while the President was winning dazzling political victories in the politically-divided Congress Mr. Stockman was discovering that the supply-side miracle wasn't going to work, not for a while anyway; that the financial community hadn't been sold on the new Reagan approach and that there would be perfectly fabulous budget deficits unless something were done to raise income or cut expenditures, or both, right away. Mr. Stockman kept preaching optimistic things to Congress while desperately reviewing the situation and coming to a different conclusion himself. He made three attempts to persuade Mr. Reagan to change his program in major particulars and was unsuccessful, or only partly successful, in each.

The problem was certainly hard enough. He wanted to spare social security and related programs which take 48 cents of each budget dollar, he wanted to spare defense, which takes 25 cents of each budget dollar. (Mr. Reagan had promised in the campaign to increase defense spending 7 percent a year, adjusted for inflation, amounting to the biggest arms buildup in history, or $1.6 trillion in five years.) Another 10 cents of the budget dollar goes into interest payments on the national debt. That left only around 17 cents of each budget dollar for Mr. Stockman to play with.

Mr. Stockman first tried to plug loopholes in the tax law, known generically as ''tax expenditures.'' Nearly everybody agrees these are wasteful and extravagant but they are protected by powerful lobbies. Mr. Stockman thought he could save $20 billion here. Mr. Reagan said, No. ''He just jumped over my tax proposals,'' Mr. Stockman reported of the President's reaction.

He also wanted to nibble at social security entitlement programs but after rashly persuading the President to accept the plan for a cut in benefits for early retirement at 62 (which brought a surly Senate knee-jerk, unanimous rejection) he abandoned that.

So how about a cut in defense? The President agreed to reduce the Pentagon budget $13 billion over the next three years but that was minuscule compared to the looming deficit.

So that leaves the President and the politicians and us in suspense as the great drama unfolds. Mr. Stockman doesn't believe supply-side economics is a panacea any more. He said indiscreet things in the Atlantic article but has apparently got Mr. Reagan's forgiveness - so far anyway. How about the next act? The article indicates one course at its close: ''. . . the Reagan White House was developing a new political strategy: wage war with Congress over the budget issues and in 1982 blame the Democrats for whatever goes wrong.''