Whatever he may lack (and in his latest book the list sometimes includes focus, self-discipline and the most basic organizational skills), you have to give Gunter Grass credit for honesty. At a time when many writers, in pursuit of big payoffs, are writing movie scenarios thinly disguised as novels, Grass has produced a novel disguised as a film scenario.

There are, of course, levels of honesty. Below the facade of scenario and novel, "Headbirths" is actually a loosely rambling essay--chiefly about world population trends and their long-range implications, but also about the 1980 German election contested by Social Democrat Helmut Schmidt and Christian Democrat Franz Josef Strauss. On another level, it is about the divisions of East and West Germany, about the futility of walls (whether the Berlin Wall or the Great Wall of China) and about the unified German tradition, embodied in its best writers, that transcends political barriers. As always in the writings of this brilliant, offhand improviser, Grass, who is the author of "The Tin Drum," sets off sparks that fly from the page in all directions--and enough of them catch fire to make the lack of focus seem relatively unimportant.

A few years ago, Grass and his wife, Ute, took a trip to India and China (two nations with populations racing toward the billion mark), where he lectured on such subjects as "The Two German Literatures." In "Headbirths," he fictionalizes this experience by inventing a German couple somewhat younger than himself, both schoolteachers interested in geography, who take a "reality-oriented" vacation in India and environs to compare the alarming population statistics with actual experience. The young couple, Harm and Dorte Peters, from a small town in underpopulated Holstein, are serious-minded, well-motivated and impeccably liberal veterans of the campus revolutions of the '60s, indelibly tinged with what Grass calls the "Central European 'Ontheonehand-ontheotherhand' parlor game," though not so much as their tour guide, Dr. Wenthien of the Sisyphus travel agency, and no more, really, than the average educated, conscientious German liberal of their generation. As a sort of table of contents near the beginning of the book, Grass lists the kind of concepts that will be juggled from the one hand to the other in the remaining pages:

"On the one hand, nuclear power plants represent an incalculable risk; on the other hand, only the new technology can guarantee the standard of living to which we are accustomed. On the one hand, manual farming provides food and employment for 800 million Chinese peasants; on the other hand, only mechanized farming methods can increase the yield per acre, thus on the one and on the other hand condemning half the peasantry to unemployment or releasing them for other, as yet unspecified, tasks. On the one hand, the slums of Bangkok, Bombay, Manila, and Cairo should be sanitized; on the other hand, sanitized slums encourage more and more peasants to leave the land for the cities."

On the other hand, when they are not gathering data to improve their functioning as teachers and alert citizens, Harm and Dorte Peters tend to worry about problems that are less cosmic--or perhaps the word is microcosmic. While they are away, their cat had five kittens, of which Harm efficiently drowns all but one, which has found a new home. The execution is done "discreetly in the bathroom. . . . The gush of water is heard, nothing more. He comes back with a plastic bag which . . . he stuffs into a garbage bag. 'They'll take it away tomorrow,' he calls out."

But, of course, that sort of thing has been discredited as a solution to the population problem. For Harm and Dorte, unlike their cat or the teeming hordes of the Third World, a personal solution to the population problem is readily available, if not exactly simple. When they are not agonizing over whether to bring Harm's widowed mother into their apartment or find her a well-run home for the aged, they are agonizing over the question of whether or not to have a child. In a sense, it is really the same question: Who should be given the surplus space in their apartment? But it is the kind of question that can torment only a small proportion of the world's population. In Europe (unlike China and India), most people have the luxury of worrying about such problems--a subject of concern far preferable to the problems of survival that demand the energy of The Third World. One basic question posed by "Headbirths" is how long the West can continue to enjoy that luxury.

But this summary makes the book seem much more focused than it really is. Along with such questions, there is a sort of travelogue on two levels (one for the Grass couple, another for the Peters couple), a lot of random satire and political commentary, some personal reflections by the author, and fragments of a movie scenario with some beautifully imagined visual-symbolic details. It is an odd, jumbled, sometimes fascinating sort of book--one that will repay the dedicated reader with occasional flashes of truth or beauty, but one that the author should have sifted and formed more carefully before allowing it to be published.