This is as good a place and as good a time as any to mark the beginning of the 1984 presidential campaign. Most of the Democratic candidates are here, assembled puportedly for the California Democratic State Convention--a nonevent of almost no significance other than to serve as the beginning of the campaign that everyone dreads. It could not have come too soon.

It is the conventional thing to say that the presidential campaign starts too early, lasts too long, costs too much and wastes the time of too many people.

It is also almost required to point out that the marathon of what seems like endless primaries and caucuses gives a distinct advantage to the candidate who holds no office and therefore has no other responsibilities other than to win friends and influence people.

This was the case with Jimmy Carter whose campaign for president started almost immediately after the previous one had ended.

All of that is true, but it is also true that without the political systems of Europe in which issues and programs are developed by well-disciplined party structures, the long campaign is a way for America to find itself.

And there is no doubt that at the moment it is somewhat lost.

There is, for instance, no industrial policy worth speaking of.

There is hardly a trade policy and nothing resembling an arms policy--nuclear or conventional--that has not been revised several times in the last two years.

We remain with a muddled policy toward China (both of them), a Middle East policy that was slow in coming and now weakened in implementation, and relations with our European allies that improved mostly because Alexander Haig is no longer secretary of state. The removal of a man, though, is not the same as a policy.

At home, things are a thorough mess. The president's economic program is a shambles--a failure for the moment and probably for the future as well.

There is virtually no program for blacks or women or Hispanics or the poor, unless it is for them to scan the want ads.

In the long run, programs will develop. But for the unemployed and for the hungry, tomorrow is the long run.

At the moment, the nation is both without ideology and without programs.

Maybe that is a good thing, since a bad program may be worse than none at all.

But if it is true that nothing concentrates one's attention like the prospect of one's death, then nothing concentrates the mind of politicians like a campaign.

Much of a campaign consists of travel and much of that is to get politicians to senseless events, but somewhere in the process they have to both test their ideas and, if they care at all about winning, listen to what is being told to them.

For that, the primaries and the caucuses are wonderful things.

They are not the mass plebiscites that general elections are. They are limited to one party and then, much of the time to party or community activists. They force candidates to deal with people who care intensely about the issues.

You can count for sure on demagoguery, but you can also be sure that some worthwhile idea will sift through.

All this is not the same as saying that the campaign is the perfect vehicle for either developing candidates or ideas. But it does force candidates to dip into the country, to sit down with women and blacks, gays and Hispanics, environmentalists and industrialists, and listen to what they have to say.

At this stage of the campaign, each person and each organization is either important or potentially important. If they have a program, they can find a candidate to listen to them.

So it begins here. The press is here--some 200 of them--and here are the candidates--seven of them.

There will be much written about who made the better speech and about who's ahead and who is not. For the moment, no one is, but if we pay attention to what is being said and if the candidates listen to what they are being told then no matter how it turns out we will all be ahead.

The campaign has begun. And not a moment too soon.