In many ways, the civil rights legislation introduced in the House of Representatives two weeks ago is an exercise in esoterica. It deals less with the substance of discrimination than with the details of enforcement: which agency should do what.

But the main thrust of the bill--perhaps even its main purpose--is to cut some space between the generally moderate Republicans who introduced it and the Reagan administration, whose civil rights record they find embarrassing.

It is the same feeling that led last weekend's Tidewater Conference to focus its most intense debate on the Republican Party's attitudes toward blacks. That gathering of 90 elected Republicans, organized by Sen. Robert Packwood, wound up passing two key resolutions on the subject. The first had the GOP reasserting its "commitment to maintaining necessary assistance to those in short-term need" as well as "programs to fully integrate black Americans into the mainstream of the private economy."

The second spoke directly to the recent civil rights proposal: "Resolved: That the Constitution guarantees the protection of all citizens against discrimination and that the federal government must therefore improve the overall efficiency and equity of its civil rights activities."

The proposal offers no new statement of rights, no new program, no new commitment. It offers only efficiency in enforcing what is already on the books.

"We are trying to deal with the major management problem of overlap," said an aide who helped draft the bill. "As it is now, people can file complaints with several different agencies that don't even talk to each other. This is a problem for the complainants and the agencies alike. It often results in a fast shuffle for the complainants, who are sent from one agency to another. For the agencies, it results in wasted effort and duplicate investigations."

The bill proposes to fix all that by placing all civil-rights enforcement responsibility in the Department of Justice. The burden of investigating discrimination claims will remain with the agencies, which will also be able to attempt to resolve the cases through voluntary negotiations. But if that fails, the complaints automatically go to Justice.

According to Rep. Hamilton Fish (R-N.Y.), who with Rep M. Caldwell Butler (R-Va.) is a key sponsor of the bill, there are, under present law, some 40 statutes and 35 agencies charged with dealing with civil rights and equal opportunity. "This (scattering of responsibility) treats civil rights law as second-rate law. We are proposing to elevate it to the status of other civil law by putting enforcement in the Justice Department where it belongs."

If the proposal would make for greater efficiency in civil rights enforcement, it would also introduce some new problems. First, it would eliminate fund cutoffs as the ultimate weapon in enforcing the law. Second, it makes the test of a discriminatory practice not whether it has discriminatory results but whether those results were "reasonably foreseeable."

But what is likely to be more troublesome for the civil rights establishment is the bill's implicit assumption that discrimination is always something done to one individual by another individual (or by a small, identifiable group of individuals).

As one lawyer who has read the bill put it, "If I work for a university and file a claim that I should have been promoted, the bill assumes that I can identify the individual who did not promote me. It does not recognize that procedures may have been set up in such a way that, in effect, the university itself has discriminated against me."

In other words, the bill does not allow the inferences from numbers that the civil rights establishment makes as a matter of course and common sense. The bill would permit the mandated hiring and awarding of back pay to any person who could prove himself discriminated against. But if the clearest evidence of discrimination was that the agency had hired suspiciously few blacks or women in areas where blacks and women are generally qualified, that evidence would not be sufficient to prove discrimination.

Sponsors of the proposal generally recognize some of its shortcomings. The point they make is that it represents a middle course between the Reagan administration's practices and what civil rights advocates might consider ideal.

And they hope that the bill, like the resolutions passed at the Tidewater Conference, will communicate to blacks that not all Republicans are their enemies.