Lapham Starts Talk Show on Books. The editor who remade Harper's wants PBS series to raise level of discourse in America. TELEVISION: INTERVIEW

LEWIS H. LAPHAM, scion of old-money San Francisco, erudite essayist, author, editor, and savior of Harper's magazine, has found a new crusade. ``I'm trying to do with books and literature what I did with ideas in the 1984 redesign of Harper's,'' said Mr. Lapham during a phone interview from his offices in New York. ``Then I was trying to make ideas more accessible with a new magazine format. Now I'm trying to make books more accessible with television.'' Creator and host of ``Bookmark,'' the PBS book program starting Sunday (see preview below), Lapham says the weekly half-hour show is simply an extension of his current editorial inclinations. ``As an editor, I like writers; I like the discussions I have with them. This show is about somehow transferring that kind of conversation to television.''

Not that Lapham isn't up against it, his success in resuscitating Harper's notwithstanding. The country has not had a nationally televised book program since John Leonard launched the short-lived ``First Edition'' in 1983. ``The perceived wisdom in this country is a trend towards visuals and a suspicion of talking heads,'' says Lapham. ``There is a problem with authors getting promoted in two minutes on air. I've done book tours, and it's very depressing. ... The level of discourse in America is higher than our network television suggests.''

Lapham also notes that, ``despite falling literacy rates, you do get the sense that there are a lot of people out there who like to read. What I'm trying to do is just make books more accessible. There is nothing elitist about this.''

As for the program's format, Lapham insists it will not be patterned after such PBS stalwarts as ``Washington Week in Review,'' ``Wall Street Week,'' and ``The McLaughlin Group.'' ``We'll use writers and a company of critics, not a panel of experts,'' says Lapham. ``I will not bring in a book and carve it up like a pig among the so-called experts.'' But neither will the show be a book report. ``I want a lively conversation that springs from a discussion of a current book.''

Lapham promises a wide-ranging discussion in the program's 26 initial episodes. Scheduled authors include Robertson Davies, Robert Coles, Margaret Atwood, Joseph Wambaugh, and E.L. Doctorow. ``We will have only one constant - timeliness,'' says Lapham. ``We're attempting to fit program dates with publishing-house schedules.''

Are there any writers Lapham won't invite on the program?

``We'll cover a wide band of authors, and at the low and high end there will be frequencies we won't use. I just don't know what they are yet.''

How about Sidney Sheldon, Danielle Steel, and romance writers? ``We might do Jackie Collins and Sidney Sheldon,'' says Lapham with one of his avuncular chuckles. ``But we'd probably do them as a genre and not as individual works of literature.''

So far, Lapham says the only glitches have been ``getting the show to move correctly. Replicating the excitement of a conversation in a caf'e or at a dinner party under the formal constraints of a television show is tough. Ted Koppel is the master at this.''

About his own TV performance - one that tends towards chalk-stripe suits, softball questions, and those sotto voce chuckles - Lapham says, ``I think I'm learning.''

What will make for success?

Lapham pauses. ``Yes, I'd like more people to read Robertson Davies, but I don't think you do a show like this in an improving way. It isn't meant to be a sermon.''