You don't have to be a conservative, a Republican or a Reagan supporter to hope that the president's recently announced economic recovery program will work.

You don't have to a be a liberal, a Democrat or a Reagan opponent to doubt that it will.

All the national opinion surveys point to an America that is willing to try the Reagan approach, that is stubbornly hopeful that the supply-siders know what they are talking about, that prays to God that the economic miracle will happen.

It is mostly, I suspect, an optimism born of desperation, not of faith in Reaganomics.

Paul Pryde is young, black and conservative. He would like as much as anyone for the Reagan administration to succeed in solving, or at least easing, America's economic woes. But he is not hopeful. I've just been talking to him about two of the key provisins of the Reagan approach: the cuts in personal taxes and accelerated depreciation for new investments in plants and equipment.

"Despite the fact that the personal tax cuts [30 percent over three years] would benefit the rich more than the poor," says Pryde, president of the Washington-based Janus Associates economic development consultancy, "this may be the only part of the president's program that will have the desired effect, and even that is dubious."

First, he explains, he personal tax reductions are premised on the notion that if taxpayers are allowed to keep more of the money they earn, they will increase their savings and investments, thereby stimulating economic growth.

It could, of course, happen precisely that way. On the other hand, we might choose to spend the extra cash, in which case we will feed inflation. Or we may invest it in "such speculative items as art, silver, gold and other commodities not used in production, in which case inflation may not get worse but economy will not get better."

And that, says Pryde, is the good news. Or as he puts it, if the proposed tax cuts for individuals offer one chance in three for success, the tax-cut prosposal for business offers no chance at all.

"By all accounts, accelerated deprecisation allowances are of greatest use to profitable, capital-intensive firms, principally large mature companies to be found among the Fortune 500," Pryde explains . "Unfortuntely, these are the very companies which grow most slowly and create the fewest new jobs.

"Simply transferring cash to them will certainly not help them grow quickly; mature companies can't. It's like trying to make gazelles out of dinosaurs by feeding them more. What the accelerated depreciation will do for the big companies is to encourage them to buy up smaller ones -- which is the only way they grow. That doesn't create new jobs.

"And since smaller young companies tend to grow more slowly after their acquisition by major corporations, the ultimate effect of Reagan's business tax plan may be not to stimulate productivity -- and jobs -- but to slow it down."

Pryde, whose academic credentials are in political science and public administration, not economics, contends that the problem with the Reagan approach is that is it too general.

"If he really wants to spur economic growth, he needs to propose incentives to spur the growth of young expanding firms. Reductions in capital gains taxes (with a differential for distressed areas) and other measures to encourage risk-taking and enterpreneurship would make far more sense in this guard than rapid depreciation allowances."

And yet the very programs that were designed to encourage just such risk-taking and entrepreneurship are under attack by the Reagan budget-cutters.

Pryde acknowledges that some of these programs -- among them the Economic Development Administration, the Small Business Administration and the Farmers Home Administration -- have not been particularly efficient but suggests that what is needed is better targeting, not a budgetary ax.

It makes sense. It is true that most new jobs in America are created by young, fast-growing companies, then it follows that the best hope for economic recovery is in the stimulation of new business, not the tax-fed enrichment of old ones.