LET US SUPPOSE, as an exercise in outrageous speculation, that Erich Segal does have something he wants to tell us. That he did not write his twin romances, Love Story and now the sequel, for frame and money, alone. That a message is buried somewhere in the cello section.

The premise, I admit, requires a leap of imagination somewhat beyond the author's own range. But otherwise there is not much to say about Oliver's Story except, it is a worthy match for Love Story .

The word which comes to mind is: crude. Segal writes so clumsily - awkward jokes and self-conscious prose, as slick as an oil smudge - I became convinced that he must do so on purpose, in order that not his lowliest reader will feed intimidated. I can't prove this, of course; perhaps he also lacks skill.

Either way, he succeeds. He has searched for and found the broad bottom of popular storytelling on which the rest of literature sits. Therefore, happy millions come to his tent. And what does he tell them? That is the only interesting question to ask, though admittedly it strains the material.

Now Love Story was easy for us. Everyone loves the death of a pretty girl, especially if her father is a fun-loving Italian baker and she went to Radcliffe and she is super-talented but still likes her Dad, whom she calls by his first name. Jenny falls in love, reluctantly, across class lines, in the accepted manner of democratic tragedy. Oliver is sensitive and rich, your typical guilt-ridden WASP, who blames Mater and Pater for not putting any pizza in his life. So they love and marry and face life responsibly (she gives up her super-career; he jogs in Central Park to keep fit) and then she dies. Slowly, with many cellos.

Only Romeo lived on for the sequel, more sensitive and guilt-ridden than ever. What happened to Oliver? Did he love again? Or did he just pine away? If that question has been nagging at you, I am about to provide the complete answer (stop reading at this point, if you don't want the suspense of the book-movie spoiled):

Oliver jogs a lot. He meets a nice Jewish girl doctor with your typical high-brow but wacky Jewish family. Then he meets a gorgeous, rich, successful WASP girl who owns a department store and also jogs.

But she is unsensitive. Oliver is busy suing the government on draft cases, marching in peace demos, pleading for the civil rights of oppressed blacks (this is, apparently, a very guilt-ridden Manhattan law firm he works for). Oliver does all this because his ancestors explotted child labor in their Massachussetts garment factory. Now here's the kicker: Oliver discovers that Marcie, the super-girl, also exploits child labor (in her Hong Kong shirt factory).

So Ollie flees from her clutches, just in time, because things were getting "serious." The nice Jewish girl has already married another doctor. So Oliver wanders home to Fall River, Mass., and discovers - surprise No. Two - that Pater all these years, unbeknownst to Oliver, has been a friend to the working man in the mill.

Thus, the answer to that nagging question: Oliver, after a few shallow adventures, goes home to the manor to become his Old Man. He takes charge of the family Business. He even becomes a Harvard Overseer. If Love Story was written for romance-satarved children, then the sequel is strictly for romance-starved parents. The prodigal jogger.

All right, it's terrible story, but what is Segal getting at? What is he trying to tell through this trite-but-brief tale?

The social message, I think, is that it's okay to believe in WASPs. As a member of that much-disparaged minority group, I am glad someone finally had the nerve to take up for us. For nearly two decades, the idea of White-Anglo-Saxon-Protestant class (the mansion-on-the-hill, the noblesse and the oblige) has been under relentless attack; now comes a nice Jewish writer to tell us that America still believes in that particular fairy tale. Erich Segal is the WASP Redeemer. It figures, does it not?

In the long run, I doubt that Segal is right. In the short run, he undoubtedly has another best seller. People like to read stories which tell them that the king is in his castle and nothing has changed (even people who wish to see things change, even people who hate kings). To imagine, however briefly, that there are such people as Oliver and Jenny, Mater and Pater, is to dream of an unblemished station in life, where perfect cellos provide the Muzak.

There is no harm done, really, except to us WASPs who were not born in mansions. How are we supposed to play in this fairy tale, when we neither quite fit as fun-loving proletarians or guilt-ridden descendents of the rich, old exploiters? My point is that the myth of WASP superiority has always been a warped mirror of other people's aspirations - not social reality - and Segal's clownish treatment makes this forcefully clear.

All of which suggests a plausible outline for the next sequel: Oliver falls in love with a militant-but-beautiful shop steward in his family's garment factory, only to discover that she is not Puerto Rican as he supposed - but a dark-eyed Episcopalian. What's more, her family used to be rich but lost it all when unconscionable conglomerates (Oliver's ancestors) drove them to the wall. Pater approves of her family, but one does not marry a shop steward.

Oliver is about to resolve this troubling social conflict when his new love is mangled in a shirt-making machine. The engagement is off, of course, but Oliver becomes even more sensitive about life. He wears her last shirt every day to remember, a blue oxford button-down. For a working title, I like: Ring Around the Collar.