'A constructive dialogue'

The people of the West can be encouraged by Washington's changed tone in its relations with the Soviet Union. It is more conciliatory, less harsh, more balanced. Especially reassuring is Secretary of State Shultz's statement to the Senate that the United States wants to engage Soviet leaders in ''constructive dialogue'' and ''need not accept as inevitable the prospect of endless, dangerous confrontation with the Soviet Union.'' Such a public posture is a marked improvement over that struck by the Reagan administration when it first came into office. Significantly, it has drawn approving remarks from both Republicans and Democrats.

It should not be assumed that President Reagan has in any way altered his basic view of the Soviet Union. Mr. Shultz did not spare condemnation of Moscow's military buildup or its ''unconstructive'' behavior around the globe. He reiterated the need to deter aggression. But the impression conveyed these days is that Mr. Reagan sees political advantage in a less confrontational tone. From the outset of his presidency he has ''talked tough'' to the Russians, a posture which has enabled him to win support for a substantial defense increase. But, with the 1984 election approaching, he clearly is building his image as a peacemaker even while reassuring the Republican right that he has not turned soft. His message to the country seems to be: The US is firmly and successfully standing up to the Russians but, don't worry, this will not lead to war.

Particularly noteworthy is Mr. Shultz's acknowledgement that the Soviet Union has legitimate security interests and that it ''is and will remain a global power.'' Yet it is not clear how the administration interprets this concept. Does it mean that the Russians have a right (as do the Americans) to try to extend their influence in such far-flung places as Angola? Does it mean that the United States will not countenance Soviet ''intervention'' in some far-off spot even though such intervention does not impinge directly on US vital interests? If the Soviet Union has the right to compete with the US as a global power, is the US prepared to accept an occasional ''defeat'' and ''lose out'' to the Russians, knowing that no Soviet geopolitical gain is permanent? Recent history shows - in Egypt, China, Indonesia, Ghana - that what the Soviets achieve one year they lose another.

Or is the Reagan administration bent on opposing the Russians everywhere and in every way - a policy that could lead to dangerous confrontation?

Such questions linger in the minds of experienced diplomats and others who have long dealt with the Soviet Union. They - and certainly a large segment of the American people - would like to see Washington shift the US-Soviet competition away from the military into the political and economic spheres, where the US has the decided advantage, and be prepared not to overreact to the Soviet presence abroad. They would also like to see progress on arms control so that the competition between the two superpowers can go on with less risk of a nuclear war.

In sum, Mr. Reagan has conspicuously disassociated himself from the old policy of detente - a policy perceived by him as having given all the advantages to the Soviet side. But, after a period of verbal confrontation, he has adopted a more accommodating stance. It now remains for him to work out the ''equitable solutions'' to US-Soviet problems which his secretary of state says the US is prepared to negotiate. If Mr. Reagan can show evidence of an improvement in Soviet-American ties before November 1984 (and assuming he runs), he probably can count on a political benefit at the polls.