INFLATION is a menace. President Reagan is dead right about that. The question is whether an unemployment rate over 10 percent is the only way to control it. Mr. Reagan's television address on Wednesday evening was a strong defense of a weak position. His purpose was to persuade the country that, however unpleasant the phase through which it is now passing, it is securely on a track that leads to better things. But is it?

At risk of making ourselves tiresome, we observe once again that there is a fundamental and dangerous inconsistency in Mr. Reagan's program -- that neat little checklist that he reviewed for his audience. The tax cut, enacted last year and coming into effect in stages, is inflationary. It collided with the tight money policy that was to curb inflation. The collision produced the continued high interest rates of the past year and the economic decline. It is only the prospect of a weak economy ahead that is bringing interest rates down now. It was probably not possible to reduce inflation rapidly and surely without a recession. But the recession need not have been so deep as this one, nor the increase in unemployment so severe.

Mr. Reagan's attack on Congress was inevitable, but unfair. The present Congress has its sins to answer for, but loose spending is hardly one of them. The deficit is more than twice the size of the one Mr. Reagan inherited. The reason for the increase is not wild spending by Congress, but the huge tax cut that Mr. Reagan proudly signed last year.

This country has fallen into a peculiar attitude toward its government -- an attitude that Mr. Reagan has accurately captured. The country wants a stronger defense, and it also wants elaborate social protections and pensions. But it doesn't want to pay for them. As long as those huge deficits persist, the economy will continue be slack and unstable. They are likely to persist forever, if presidents keep telling people that taxes can be reduced and the budget balanced without doing anything very serious to anybody's benefits and entitlements.

Mr. Reagan calls on Americans to return to prosperity by "staying the course." But where is that course leading? It appears to keep heading downward when, according to the map, it should have turned up by now. Mr. Reagan says that all the world sees that upturn just ahead. On the contrary, hardly anybody seems to see it. And when it comes, what will it bring with it? A recession always reduces the inflation rate, at least temporarily. The great challenge for American politics, and politicians, is to achieve stable and prosperous growth without raising that inflation rate again.