The president and his chief aides have been refining and publicizing a composite view of the Soviet Union that starts in insight but verges quickly on illusion. One can't be too dogmatic in these maters, but my fear is that a policy based on this view could, in the name of strength, weaken the American position in the world.

The insightful aspect is that the Soviet Union is two things: a country in trouble and a country that can cause trouble. It is sterile in ideology, beset economically, facing restiveness among its allies and perhaps incipiently among its citizens. At the same time, it has a formidable and growing military capability and a clear tendency, if not a spasmodic compulsion, to test its new power globally.

The inconsistency between these two elements is only superficial. The late Vince Burke of The Los Angeles Times used to say there were two Soviet societies or economies, the open one that you could see didn't work and the secret one that produced, and well, for the military. To keep one eye on the fault lines of Soviet reality while keeping the other on the Kremlin's drive for power seems to me quite sensible. It is even possible to suspect, with the administration, that the Soviet Union may be most dangerous in the period just before its internal weaknesses take an evident toll.

But anyone who has read Soviet history has got to be a bit amused, and sobered, at the length to which the president and some of his aides tend to carry this otherwise prudent view. The echoes are there, though the administration does not show signs of hearing them.

Since the first days of the Bolshevik regime in 1917, its Western foes have been predicting its decline and eventual fall. This is usually presented as a fate arising from the regime's own inescapable contradictions. Often, as now, these Western prophecies have had to them a ring of historical determinism recalling nothing so much as past communist predictions of the demise of capitalism. Those latter predictions, of course, we have mocked for decades. The Soviet attitude now is the same.

Reagan and his aides and supporters burst with confidence in the American way. They portray their confidence itself as an instrument of national revival and foreign policy, and they move on easily to mirroring denunciations of the Soviet way. To the extent that this reflects a healthy appreciation of value differences, this is fine. When it becomes a banner of ideological war, however, difficulties arise.

That crusades don't promote compromises is, of course, precisely why a good number of people like the Reagan approach to the Soviet Union, which they regard on the 'itler model as an indelibly adventurous power with which workable compromises are out of the question. Others, including me, take a different view: that the Soviet Union is adventurous but pragmatically so, that certain accommodations are possible and desirable, and that at least they should be given a fair try.

If you think the Soviet Union is not only morally unworthy but also headed toward eventual collapse, then it is but one step to standing back and letting history spell itself out and one more step to moving in and giving history a little shove. Along the way there may be moments when practical considerations, such as the clout of American wheat farmers or the need to accommodate allies, force you to deal with Moscow. The basic thrust, however, calls for not dealing, for not linking the American and Soviet futures at all, for keeping the pressure on.

It doesn't seem to be clear in the Reagan view whether Soviet communism is to wither away or to be swept away or to be transformed into something else or just to be brought to heel. But there is a conviction that the regime (now 63 years old) is transient as well as illegitimate, that its economic, imperial and ethnic frailties are such that a policy of strength and endurance will pay off in a reasonable time, and that a change of regime or even a change of heart will produce a suitable partner for the United States.

I think President Reagan is being tough to a fault. He is mortgaging his policy to a single, extreme, arbitrary and historically unproven concept of Soviet power. By so doing, he risks continued strains with friends and allies, whose politics and psyches are geared not for a Reagan-type all-or-nothing roll of the international dice but for nursing their chips and staying in the game for the long haul.

Reagan cannot except to profit indefinitely from the still-pervasive sense that he is correcting, necessarily, for his predecessors' errors. As time goes on, Americans are bound to become more sensitive to the budgetary and political implications of his policy. The relative consensus prevailing now may cloud. It could take as little as a year.