Bemoaning the early advent of presidential politics is about as futile and -- by now -- tiresome as all those sighs about how Christmas decorations go up too soon in the stores. Two years to New Hampshire -- the current time on the political clock -- is hardly too soon for our electioneering to begin, given its distinctive character. For this is the country that invents its politics anew every four years, and to do so takes time. The process on which we are about to embark involves not so much responding to a known leader who represents our longstanding sympathies, whatever they are, as talking ourselves into supporting someone, often someone we've never heard of and usually someone of whom we know very little. There is something profoundly superficial, which is to say, deeply shallow, about this, and predictably enough it often leads to a subsequent crash of disappointment with the chosen leader. Is this about to happen again?

It easily could. This will be the first election in 20 years in which an incumbent president will not be running, so both parties will be going through these strange exercises in candidate fabrication. In fact, they already are. Americans have exactly three ways in which they decide whom they are for for president. Two of them are peculiarly inorganic -- detached from feeling and instinct, highly cerebral, arrived-at results as distinct from warmblooded, inevitable ones. And you are beginning to detect signs of both of these fabrications now.

The first is entitlement. It is simpler than the second to describe, being merely some combination of a sense of fairness and duty in the constituent and a conveyed message from the candidate that he is the titular leader, the legatee, first in line -- i.e., entitled, the eldest son of the duke. Vice presidents generally have this working for them, as do once- defeated candidates for president or vice president. They strengthen the message by gathering a bewildering array of endorsements from other politicians, but these are generally given in a pro forma, even opportunistic way, conveying to the public only that the endorser was afraid he might miss the train. Walter Mondale had this kind of "strength" early on, and it is worse than illusory: it also creates an image of arrogance and unfair advantage that begins in short order to repel. George Bush is going to have to look out for this. Entitlement candidates' support tends to be their downfall.

The second way of choosing a candidate resembles the hiring process, or even the headhunting executive search. It begins with a highly intellectual judgment as to what combination of qualities is needed and then proceeds to a scrutiny of available r,esum,es, no prospective employee being too obscure or improbable to be considered. To some extent the detachment proceeds from the fact that the people choosing this candidate, whether they are political bosses or merely voters, tend to be looking for someone who will please someone else. So the discussions are pretty much without feeling.

Some large part of Jimmy Carter's support developed this way. I remember feeling that Carter had an almost perfect political r,esum,e for what ailed the Democratic Party in 1976: farmer, military man, racially reconstructed deep Southerner, etc. You hear people talking about other prospective candidates this way now. Meaning no harm to any of them, Bruce Babbitt, Charles Robb and Richard Gephardt, among others, seem to be the beneficiaries of this kind of bloodless, theoretical calculation.

Certainly it reached its starkest form in the Democratic vice presidential selection process in 1984, when a parade of walking demographic statistics turned up for conversations with Mondale -- a Hispanic, a black, three women and so forth, none of whom he knew much better than the nation at large did. On that occasion the procedure itself was elevated to the status of a Good Thing, a demonstration of fairness, openness of mind, determination to find the ideal one. I thought it was awful, however, as did many other people. It appeared to be simulation politics at its most empty worst. Surely by that moment our politicians should be expected to know whom they want for the No. 2 spot and not be placing want ads.

There is a third kind of candidate whose adherents are different from the others. They are true believers. These are the candidates who have excited a popular movement, who have come to embody a set of passionately held ideas. Such candidacies are rare these days. They are powerful. And they are almost invariably despised and/or feared by the pastors and managers of our national political life. Conventional wisdom far prefers the candidate of entitlement or construction-to-specifics. It sees the candidates of popular political movements as being "ideological," inflexible, unreliable and ultimately dangerous. Sometimes, of course, they are. But for all the faults, there is something reassuring and exhilarating about watching a genuine alliance of sympathy and respect develop between a political leader and his constituency in these affairs, whether it is the campaign of Ronald Reagan or Jesse Jackson or Bob Kennedy, to name a few of those who have had the moment and the gift.

And what about 1988, when Ronald Reagan, the very model of the popular-movement candidate who made it, will be gone? Well, Jesse Jackson is back. Jack Kemp comes into the field with a following of this kind. No Democrat does. So if you believe that neither Jackson nor Kemp will make it and that there is no popular movement Democrat so far in the field, it seems as though we will be going the other way again two years from now. If this is going to be true, I have some advice. Let's turn our attention from worrying about the well-documented dangers of overheated political passions and ideological fervor to the dangers that may attend yet another national blind date.