Throughout his political career, President Reagan has been both blessed and cursed by his proclivity for delegating basic decisions to subordinates.

As governor of California, where Reagan at first knew so little about public affairs that delegation was a necessity, this tendency plunged him into needless confrontations but ultimately resulted in successful welfare and tax legislation.

In his first term as president, Reagan chose a talented if sometimes fractious team that advanced his basic goals of reducing the federal government's role in domestic affairs and building up the military establishment.

But Reagan paid a huge first-term price in foreign policy for his delegating. He lost an early opportunity to win approval of the MX missile he now claims is a strategic necessity. He wound up with an open "secret war" run by the Central Intelligence Agency in Nicaragua.

And he allowed powerful Cabinet officers and their aides to develop competing strategies for negotiating with the Soviet Union.

Reagan is probably right in contending that the Soviet leadership was in such flux during his first term that successful negotiations on arms control were impossible. But in dealing with the new Soviet leader, Mikhail Gorbachev, Reagan finds himself haunted by unresolved differences within his administration.

Administration officials quickly have developed considerable respect for Gorbachev. He is, as White House chief of staff Donald T. Regan put it last week, "no cream puff."

Despite Gorbachev's tough talk, however, the prevailing view at the White House is that he is a shrewd political leader who wants to sit down with Reagan and stabilize relations. Some think that Gorbachev is willing to sign an agreement that would reduce the level of strategic nuclear weapons.

The deep private concern among some Reagan intimates is that the history of the first term is repeating itself when there is realistic hope for progress in U.S.-Soviet relations.

On issue after issue, divisions between one group of influential strategists and another, often reflecting the institutional combat between the State Department and the Pentagon, are sending conflicting U.S. signals.

The differences surfaced sharply after a Soviet sentry in East Germany shot and killed Army Maj. Arthur D. Nicholson Jr. in March. The State Department thought it had worked out an agreement to prevent further incidents, but Defense Secretary Caspar W. Weinberger, who had just returned from the Nicholson funeral, objected to what seemed to him to be a pat diplomatic rationale for an act of murder. The Soviets responded by repudiating their agreement.

Last week, the day before a major Reagan address on U.S.-Soviet relations, Richard N. Perle, assistant secretary of defense for internal security policy, expressed his "personal view" that the United States should no longer observe the nuclear force limits of SALT II, which the United States has not ratified.

Perle's view is not shared by Secretary of State George P. Shultz or national security affairs adviser Robert C. McFarlane, and Reagan has borrowed from both sides of the argument in speaking to the Soviets. The day after Perle's testimony to a Senate committee, the Soviets seized their propaganda opportunity and said they would abide by SALT II limits.

Reagan's speech to the European Parliament, the subject of a separate struggle between McFarlane and White House communications director Patrick J. Buchanan, was intended to signal a willingness to negotiate.

But it, too, contained mixed messages. Crammed with old but useful proposals for easing tensions and promises to abide by existing treaties and seek new arms reductions, it contained a warning that a new Soviet mobile missile could be considered a "first-strike" nuclear weapon.

This opinion, advanced by McFarlane before Reagan's speech, is disputed by some experts who say that the primary purpose of a mobile missile is to survive a first strike rather than to launch one.

A reasonable case can be made for any of these competing contentions. But it may be difficult for the Soviets to sort through the conflicting messages.

The Great Delegator gave some stirring speeches last week, and he is sincere in wanting to improve relations with Moscow. It is unlikely that he can succeed, however, unless he resolves to make some command decisions on arms control and U.S-Soviet relations. The divisions within the Reagan administration are too profound to be settled by anyone except the president.

Reaganism of the Week: After Communist delegates walked out of the Portuguese parliament last Thursday, Reagan said: "I'm sorry that some of the chairs on the left seem to be uncomfortable."