Four times in the past two decades, a presidential decision has set the American economy on a course that drove it into deep and prolonged trouble:

In early 1966, as the costs of the Vietnam War rose rapidly, President Johnson's advisers pressed him to ask Congress for a tax increase. He delayed for a year and a half, generating the first phase of the long cycle of high inflation that persists today.

In late 1970 and early 1971 President Nixon, determined to create a wave of prosperity for the 1972 election, opened up every valve he could reach. That led to the second phase of the long inflation, which, aggravated by the oil crisis, led to the recession -- until then the most severe since the 1930s -- that began in late 1973.

In 1977, on taking office, President Carter pushed hard to get the unemployment rate down. With unemployment over 7 percent, he couldn't believe that there was any danger of inflation -- but the inflation rate was approaching 10 percent even before the second oil crisis arrived two years later.

Last Monday, with the federal budget deficit at $210 billion, President Reagan flatly and categorically refused to countenance any tax increase -- even the very limited one that a group of Republican senators had proposed. Perhaps you could argue that the central error in the Reagan economic policy was the huge tax cut in 1981. But at the time, the president and some of the people around him believed firmly that the tax cut would set off a sustained period of business expansion and rising incomes fueled by high savings and investment. Events have not borne out that hope. If the original tax cut was a mistake, it was a greater mistake this week to refuse to recognize it and correct it.

President Reagan now wants the House and Senate to agree on a budget resolution for the coming year. But it's hard to see that the passage of a resolution will make any difference by merely ratifying another year's procrastination on the deficit. Mr. Reagan himself has no clear plans for reducing it, nor does he seem to think that reducing it is very urgent. Sometimes he speaks of the possibility that growth will solve it -- a possibility that, after four years, has shrunk to the vanishing point. Sometimes he speaks of large unspecified spending cuts that he blames Congress for never having made -- although Mr. Reagan supports no spending cuts that would change the deficit more than marginally.

This weekend Congress will go off on holiday until after Labor Day. The serious and sustained attack on the deficit that the president refused to join this summer is not likely to be mounted next fall, in the last weeks of the session. The attack that is not begun this year is not likely to be attempted next year, with the election campaign under way. It is hard not to conclude that Mr. Reagan kicked away an opportunity this week that will not come again in his presidency.