President Reagan's foreign policy "appears to be steered in critical areas by illusion, inertia and nostalgia." Detente is a "grand illusion." Reagan is wrong in declaring that the United States and the Soviet Union have a common interest in avoiding war. Under Reagan, the "continued socialization" of America has "proceeded apace."

These are not the contentions of an obscure right-wing critic of the Reagan presidency. They are the written views of Reagan's new director of communications, Patrick J. Buchanan.

As the former Nixon speech writer returns to his ideological labors in the White House vineyards, most commentary has focused on Buchanan's jaundiced view of the "big media," which he described last year as the "polemical and publicity arm of American liberalism" and the "strategic reserve" of Walter F. Mondale.

Some reserve, some publicity arm. How powerful this "big media" must be that it was able to put Mondale over the top in Minnesota.

Somehow, Reagan has overcome the heavy obstacles strewn in his path by the news media. Lacking Nixonian guidance, he has treated reporters as human beings rather than a collection of enemies. Reagan is his own best director of communications.

Nonetheless, there is something discomforting about media reaction to Buchanan's appointment, something that indicates that he may have a point in suggesting that the big battalions of journalism are afflicted with self-importance. Too many of us have reacted by probing Buchanan's view of the media, perhaps because we are preoccupied with ourselves.

There is a more important dimension to the Buchanan problem. Nothing requires a president to name a director of communications who respects the media, but common sense commends the choice of someone who favors the policies of the president he represents.

Buchanan's columns of the last two years suggest that he is not that someone and that he marches to a more militant drummer than Reagan, especially in foreign affairs.

Reagan has promised repeatedly to seek an arms control agreement with the Soviets, while pursuing his Strategic Defense Initiative to find a non-nuclear defense against nuclear missiles. The president's liberal critics see these objectives as incompatible, and Buchanan agrees with them.

"They are probably right," he wrote in a Dec. 19, 1984, column. "But, ultimately, the choice is national security or arms control."

Repeatedly, Buchanan has taken dead aim at what he sees as accommodationist policies of Reagan's secretary of state, George P. Shultz. Buchanan contended last March that "a nationalist foreign policy, grounded in the security interests of the United States," would have ejected the United Nations "the U.N. spy center," in Buchananese from the United States, thrown Poland into default by calling its loans and demanded veto power over World Bank loans.

These policies, Buchanan wrote, were opposed principally by "the international bankers and foreign ministers . . . and the parasitical class of international bureaucrats." But in every case they also were opposed by Shultz and Reagan.

After Robert C. McFarlane became national security affairs adviser, Buchanan complained on Oct. 21, 1983, that he lacked a "Reaganite view of the world," and wrote that "everywhere you look, you see being bolted back into place the policies against which Reagan ran . . . . " When Reagan proclaimed 1984 as a "year of opportunities for peace," Buchanan wrote sarcastically on Jan. 25, 1984, that pressure from Europe, the media and the Democrats had "converted Mr. Reagan into a president of the Order for Peaceful Coexistence."

Buchanan also finds Reagan's domestic policies too liberal. Slightly more than two weeks ago, Buchanan wrote a column in which he approvingly cited Charles Murray's program of "scrapping the entire federal welfare and income-support structure for working-aged persons, including AFDC, Medicaid, food stamps, unemployment insurance, workers' compensation, subsidized housing and the rest."

Such a "seemingly Draconian solution," Buchanan wrote, is "worth consideration, worth a try." How does this jibe with the president's renewed promise to preserve the social safety net? How does Buchanan speak to the world for a president whose policies he has so often scorned? Reaganism of the Week:

Speaking to religious broadcasters last Monday about the menorah, the ceremonial candelabrum that symbolizes Hanukah, the Jewish festival of lights, Reagan said, "In December, when I looked north from the White House, I would see the huge menorah, celebrating the Passover season, in Lafayette Park."