CONVENTIONAL POLICY to reduce inflation pushes up unemployment, as President Reagan has discovered. Conventional policy to reduce unemployment pushes up inflation, as President Carter demonstrated. With the single exception of Japan, all of the industrial countries are caught in a trap between these two conventions.

Let's be truly radical for a moment. Let's consider, merely as an exercise of the imagination, how things might work if wages, instead of being fixed for a job, floated with the state of the economy. On the opposite page today you will find a brief essay on the subject by Martin L. Weitzman. It is disarmingly elementary, a good teacher's model, but he is opening a genuinely important line of inquiry. The trouble with most proposals for flexible wages is that, when a recession comes, they would cut demand and create even more unemployment. Mr. Weitzman's suggestion differs; it is designed to maintain pressure toward high employment.

A tradition of high fixed wages is not well adapted to a period like the present one in which the character of industrial production changes rapidly and continuously. In a time of great technical innovation, hot foreign competition, floating currency exchange rates and volatile interest rates, an insistence on fixed wages may be a formula for continuing high unemployment.

True, the alternative is not everybody's first choice. Who wants to take a job without knowing precisely what it will bring? But suppose the choice is put another way, between a world in which wages fluctuate and one in which employment fluctuates. Is it really clear that life is more secure when the alternative to a fixed wage is none at all?

A mild warning: Mr. Weitzman's proposal is not quite so simple as it looks at first glance. You may be inclined to dismiss it as unrealistic, and too wide a departure from present practice. But with 11 million people now out of work, and all the forecasts indicating no improvement soon, it is not very useful to wave away every new idea with the objection that it's not the way this country does things. The way this country does things is not working well, and the time has come to expand the range of discussion.