THAT WAS a powerful speech Ronald Reagan gave before the NAACP convention in Denver yesterday -- eloquent in its castigation of the evils of racism, sharp and clear in its delineation of the Reagan position on combating those evils and attention-getting because Mr. Reagan had braved an audience known to feel deeply aggrieved by him and to be out of sympathy with his intentions. His allusions to the pariah hate groups that are renewing their loathsome efforts around the country, to the horror of Atlanta, to the unequal burden of economice hardship borne by blacks were the right ones. And yet there is really no testimony Mr. Reagan can offer just now, in the wake of his cataclysmic budget cuts and at a time when the course his government will take on a wide variety of civil rights issues remains uncertain, that could be expected to reassure those who fear that the Reagan years will mark a terrible setback for political and economic progress for blacks as a whole.

Some part of this apprehension, anyway, is unfair. The president is correct in that aspect of his analysis which holds the perpetuation of dependency among poor blacks a deadening and unworthy effect of some of the federal government's efforts to "help" blacks, and also in his insistence that a strong economy, not just strong support for certain government programs, is esential to the well-being of blacks as a group in this country. When he observes that "indurtries in which blacks had made substantial gains in employment, like autos and steel, have been particularly hard hit," he makes the point beyond argument.

But there are degrees in these affairs. You can believe with the president, as we do, that much of the government intervention on behalf of poor minorities has failed and some even made things worse, and yet also vigorously reject the notion that this is grounds for doing away with these programs wholesale.Mr. Reagan's budget has given small comfort to clacks in this regard; the cuts in relevant areas have often seemed indiscriminate and insensitive. His Cabinet members speak of alternative methods of achieving desirable racial goals, but so far they seem much more eager to dismantle than to replace.

The larger replacement Mr. Reagan has in mind, of course, is one that will in its way transcend the various programmatic civil rights disputes (e.g., over the Voting Rights Act renewal, school integration and affirmative action, to name a few). It will be the replacement of present economic distress and degradation by an economic and social system Mr. Reagan hopes will transform the very nature of minority life in this country. There will be jobs and hope and equity and upward-bound progress and the dignity that comes from full integration into a healthy and competitive by fair and stable system.

It sounds terrific. But this vision of wholesome times ahead rests in large part on the same economic assumptions on which Ronald Reagan has rested so many other hopes. Mr. Reagan risked something personal and political yesterday when he walked into that hall to speak directly to people who had gone on record, by their resolutions, as having no great use for him. He risks something else, something larger, in hinging so much on uporoven and questionable economic theories. But however much Mr. Reagan risks, he is nowhere near so much in danger from a failure of his theories as are those disadvantaged black people who are being asked to repose their modest hopes in the correctness and success of the Reagan idea.

It is for this reason that people who doubt neither the president's conviction when he passionately denounces racism, nor his sincerty in believing that his economic program will in time do the trick, believe that he must offer black Americans something more. That something is evidence, in the daily workings and policy choices of his government, in its attitude toward the civil rights statutes that remain on the books and have made such a difference, that the administration of Ronald Reagan is as committed to the furtherance of racial justice in this country as Mr. Reagan himself proclaims it to be.