Presidents Truman, Eisenhower and Nixon developed comprehensive policies for dealing with concrete problems in Europe, the Mideast and Southeast Asia. Outsiders looked on those policies and baptized them as, respectively, the Truman Doctrine, the Eisenhower Doctrine and the Nixon Doctrine.

The Carter administration has not yet developed a policy for dealing with the concrete problems it faces in Southwest Asia. But it has leaked word that the president will enunciate in a major speech, perhaps this week, a Carter Doctrine. How come the backward approach?

The answer, I think, is that the president isn't sure what he wants to do and doesn't know how to do it. A split of yin and yang dimensions still divides his main advisers. The doctrine has emerged as a means of presenting to the public a masterful president. But in the process, a crisis, serious from the start, has become truly dangerous.

The seat of crisis is the vast expanse that runs from the northwest corner of the Indian Ocean to the Himalayas. Imperial Iran used to be the protecting power in the region.

The departure of the shah a year ago, however, pulled the plug. Ayatollah Khomeini not only proved unable to assert control over submerged ethnic groups at the edges of Iran; he also distilled a brand of Islamic fundamentalism that posed problems for governments in all the neighboring countries -- the radicals in Iraq as well as the royals in Saudi Arabia, and the pro-Russian bosses of Afghanistan as well as the pro-American bosses of Pakistan. As a result, what had been a relatively calm area suddenly became the cockpit of world politics -- the new Balkans.

The Russians perceived the change. By moving the Red Army into Afghanistan last month, they asserted control over a country about to come unstuck. They also positioned themselves for shots at Pakistan, Iran and the Persian Gulf. They thus handed Washington a major security headache.

The president and his advisers felt, rightly in my judgment, a need for strong response. The arranged quickly for a drastic cutback in economic ties with Russia, including an embargo on grain sales. But as they turned to further measures, an old split reasserted itself.

Secretary of State Cyrus Vance and Secretary of Defense Harold Brown, rightly in my judgment, favored reversible actions. They wanted to keep open the door for a revival of detente and arms control.

In that spirit, the administration moved to condemn the Russians at the United Nations -- a mere gesture. It talked of possibly boycotting the Olympics -- another gesture. It appealed to the Europeans and Japanese in ways that caused those allies to pull back. It talked of "complementary" actions with the Chinese -- but not of weapons. It spoke of military installations around the Gulf -- but only facilities, not permanent bases. It urged upon Pakistan military and economic aid -- but drew back before a security guarantee.

The president's White House advisers were, also rightly, frustrated by this process. They moved around the regular bureaucracy to dig out other alternatives.

Out of that process there emerged the notion of a policy statement akin to the doctrines associated with past presidents. Once broached, that idea asserted itself irresistibly as a way to convey the impression of an administration dealing with major problems in a big way.

The excruciating diffculty of fitting all the pieces together can hardly be exaggerated. History has thrown the world a curve in the form of Islamic fundamentalism. There is no sure way to hit the ball.

But the course followed to date by the administration invites a strikeout. Resort to the United Nations advertises impotence. Halfhearted approach to allies and friend yields an accumulation of public rejections. Talking vageuley to the Chinese is provocative. So the Russians now find themselves with little to lose and lots to gain -- a truly perilous condition.

In these circumstances, what started as a public relations requirement has become a requirement of the real world. The president needs to assert a comprehensive policy in ways that give a clear and steady signal to this country, to its friends and to the Russians. Besides the general principles, he also needs to include some military action that would establish in the area an American presence as a trip wire sure to trigger response in the event of any further Russian steps. In that way, this country would arrest the rapid deterioration of events and give the world what is most needs now -- a time out. The basic fact is that the deterrent deters. Any reluctance to put American forces on the spot in Pakistan only increases risks.