When Federal District Judge W. Arthur Garrity Jr. on Nov. 29 made clear that he - not the elected Boston School Committee - will ultimately decide which schools close here, he continued the judicial overlordship that has driven half the city's white students out of the school system.

What makes this remarkable is that the school committee is no longer the bastion of bitter-end anti-busers. Its chairman, Kathleen Sullivan, provides moderate leaderhip that accepts the inevitability if not the wisdom of court-ordered busing. She led all candidates for reelection Nov. 8, when Boston's voters elected the committee's first black (a moderate) and defeated its foremost anti-busing zealot.

But the new school committee is treated no differently from the old school committee by Judge Garrity. He and what Miss Sullivan calls "those crazy experts of his" are not surrendering control. That suggests continued white exodus from the system, in which Garrity's rule has brought soaring per-pupil costs without improving education. "The victims are the kids," Sullivan told us.

This is stage II of Boston's busing. Violence and demonstrations have ended, and one-issues politicians are driven from office. But liberals elsewhere make a mistake if they interpret this as approval of busing. "The people don't go out and chant slogans," Sullivan told us. "They merely creep out of the system."

Unable to overcome the judge, they escape him. Since Garrity's busing order in June 1974, white school enrollment has dropped from 58,000 to 29,000. Experts had predicted a normal yearly loss of 3,000 whites, due to population patterns - 12,000 over the last four years. So, because of busing, an additional 17,000 white students have left the system. In a city where the black population is only 20 per cent, the blac school population is nearing 60 per cent.

A classic case is the Morris School in the West Roxbury section, which in November 1974 had an all-white enrollment of 347. A 1975 "masters' panel" of distinguished citizens (appointed by Garrity) recommended, as part of a citywide plan, a total of 260 whites and 70 blacks at Morris. But Garrity rejected the whole plan and redrew school boundaries to ensure a 50 - 50 racial mix. The result: Current enrollment at Morris is 23 whites and 123 blacks. The whites have all but disappeared.

Nor has the exodus concluded. A Garrity-ordered school reassignment last summer (later suspended) led many white liberals finally to give up and put their children in private schools. Garrity's resistance to the special program for gifted students has lowered another possible barrier to flight from city schools.

The decline of the Morris school enrollment, down from 347 to 146 in three years, is no extreme example. Unfilled classrooms, along with busing costs, have boosted annual costs per pupil to over $3,000 (and $5,500 at embattled South Boston High).

Mayor Kevin White, the tragedy is that high costs have produced education no better and likely worse than it was. But Garrity and his chief expert, Boston University Dean of Education Robert A. Dentler, have fought school closing as a covert attempt at resegregation.

When we interviewed Sullivan and Dean Dentler on television in September 1976, Dentler steadfastly denied any white flight. "It was then for the first time," Sullivan told us more than a year later, "that I realized how little those people understood what was going on."

Ignorane of political realities is characteristic of colonial rule by overlords who do not live in the political unit they control. Garrity lives in suburban Wellesley, Dentler in Lexington.

Garrity obviously regards Boston's politicians and people with intense suspicion. Although he may relinquish school control in about two years, Garrity exhibits a paternalistic need to protect Bostonians from themselves - another colonial characteristic.

Constitutional scholar Raoul Berger, in "Government By Judiciary," concludes: "The judges might begin by curbing their reach for policy-making power, by withdrawing from extreme measures such as administration of school systems - government by decree - which have disquieted even sympathizers with the ultimate objectives. Such decrees cannot rest on the assertion that the Constitution demands busing, when in truth it is the justices who require it in contravention of the framers' intention to leave such matters to the states."

For Garrity to take that advice would be welcome news for Bostonians and their elected school committee, who want nothing more than to run their own affairs without the good judge's protection.