Ronald Reagan put away all of his primary opposition a long time ago. Since then he has been trying to overwhelm an even more menacing opponent: the image of himself as a preposterous old gunsmoke gaga who simply cannot be taken seriously as a prospective president by millions of sane American voters. This -- the image, not the man -- is what Jimmy Carter passionately wants to run against, and when he has already begun to. But I think Reagan, in the course of being nominated last week, and over the past few months in general, has done an enormous amount to dispel it. His triumph to date is that the Carter people's adjectival attacks on him -- "trigger-happy," "elitist" and so forth -- already sound out of focus. He may well end up making Carter run against him , rather than against the caricature.

Let's take it element by element. First there was the Old Man business, politely known as the "age issue." Actualially, Regan is no better a bet now than he was six months ago -- in fact, he is a six-months-worse bet. But the prune-face cartoons seem as out of place as do some Carter's verbal attacks. Merely by beating the whole collection of younger, spryer, ostentatiously jogging competiton and by his behavior in his public appearances, Reagan has pretty much eliminated that feeling, so strong among the pundits last winter, that he was simply too old to be plausible as a candidate.

Next came Dumb, which also was victimized by the fact of Reagan's winning in the primaries. How dumb can you be and still manage to dispatch, say John Connally and the Fortune 500, George Bush and the Eastern political establishment and all the many others? Reagan was a slave to the little white index cards, came the reply; he was programmed, simulated, a kind of talking robot who didn't really grasp the positions he was espousing.

Maybe this is so -- I don't know. In my own close-up observation of him at an interview last month, he seemed unaware of and unschooled in the policy implications of some of the things he talked about. But he surely didn't seem to be this empty-head of much public imagining, and his appearances on a number of TV programs have also broken through the charges of intel- lectual deficiency. Wrong is different from Dumb. And so is Unfamiliar or Inexperienced. I think the effort to portray Reagan as a dummy, which reached its height a few months back with a spate of stories about how the poor thing couldn't understand his briefing papers, has failed.

Part of the Dumb charge, of course, was based on the Simpler Times and Nostalgia count in the indictment. We still hear a lot of this. Reagan certainly does talk about and yearn for an "old" standard of family cohesion, for instance, and he is much made fun of because of it. His critics say that it is unmodern of him, that the family has greatly changed in contemporary times. In this, they betray their own limited perspective, believing all change for the less conventional has come in their 1960s and 1970s time, whereas the wondrous, peaceful orthodox arrangement Reagan yearns for has probably never existed as an absolute standard. Just ask Orestes and Electra and Clytemnestra, if you don't believe me . . . and George Babbitt. Ask Hester Prynne what she did to win her scarlet letter. g

I am unable myself to get riled up about the Simpler Times and Simplistic Yearnings issue because it is, first of all, a theme that has run through Western culture since at least the time of the elder Cato, and second because it is as firmly implanted in th e left as in the right. When it is expressed by those who abominate Reagan for it, however, it goes by another name -- such as "greening," for example. The back-to-pancakes-made-from-scratch and down-with-technological-progress school of politics is a manisfestation of the same thing.

The Mad Bomber charge comes next. I myself am not crazy about some of the defense theory being put forward by the candidate, and, God knows, he has taken some positions that would curl your hair. But again, I think Carter's attack on Reagan in this connection as a madcap, hot-blooded, impulsive war starter is simply dstroyed by the persona of Reagan as projected in his television and other appearances. He clearly has a temperament different from that which is continually invoked against hiim as a meance to the continuation of life on the planet.

Ah, but of course : he is an Actor -- with which we reach the next element of the disparaging perception. That is true, but if this whole political trip is "an act," it just doesn't have the character of one. I was interested, watching Reagan accept the nomination in Detroit, to note that the speech text was much better than his delivery of it, which was full of bumbles. Some actor, I thought -- and then: but what if this was the quintessential "act," a Gipper-like pretense at not being a slick actor? No. That would require, as would the whole Actor theory, a degree of guile that just self-evidently isn't there.

People have seen this. In fact, Reagan's lack of guile is one of the things that he has going for him, even though it also represents a danger (presidents need guile). In my view, he really got taken, for instance, in the Ford-negotiation blunder. But unlike what might have been expected from other politicians, including one he is running against, he did not shoot back with a profession that he had always wanted only George Bush and the whole thing with Ford had never really been taken seriously by him, etc. He said he had tried it and it hadn't worked. In fact, Reagan won the nomination over the months with what seems to have been an unusually aboveboard, uncrooked and umcompromised campaign, and he came out of the convention with this value intact.

Reagan the candidate and the platform he is running on both raise huge unanswered questiions, in my judgment. There is plenty to argue with and a lot to worry about there. But his candidacy and what it embodies are worth arguing with. They are not a joke. My guess is that Carter is going to have to fight him, to stop waiting (and praying) for the big goof, to engage Reagan on real-issues terrain. He is inot going to be able to win by means of protracted, satircal putdown.