Fatherhood <i> by Bill Cosby (Doubleday: $14.95; 216 pp.) </i>

It’s bizarre, the author concedes at the outset, but that’s never stopped consenting adults from doing it--he and his wife, for example, five times. Making babies, he means, and then raising them up despite all the attendant aggravations that parents can fall heir to, from colic to car to college--even to the day the grown-up kids move back in. Maybe we’ll all laugh about it one day, but for those in its midst, the entire procreative process seems inexplicable, irrational and sometimes hopeless. You’ve noticed the vacant-eyed men who haunt bus terminals “poignantly staring into space”? “They are fathers,” says Bill Cosby, “who have run out of ways to get their children to do the right thing.”

All the same, fathering has been a kick for Cosby, no matter that his five progeny, like most others, have had that unerring knack for presenting their sire with a lifetime of demoralizing episodes (soap-on-a-rope, for heaven’s sake, on Father’s Day). Thus, the point of his book is to encourage and to celebrate the doughtiness of dads like him. That, and for author and publisher to latch onto the suddenly topical theme of parenting.

It has lately been determined by experts, you see, that mothers needn’t have all the parental fun; participatory, attentive fatherhood can be a good thing, too. “Fathers are often just as interested in and delighted with their newborns as the mother,” is just one kernel of insight harvested from a silly pretentious afterword by Harvard psychiatrist Alvin F. Poussaint.

As a kind of acting script in prose form, “Fatherhood” not only offers Bill Cosby’s TV fans an excuse to read a light book (big print; short chapters) but, chockablock with chuckles, it serves up familiar situation-comedy fare. “The Cosby Show’s” background laughter isn’t audible, and you can’t see Cosby’s lips pursing and eyebrows arching, but you know all three must be happening.

Take by take, then, Father Bill, the helpmate mother and the provoking kids contend with one another:

On distressingly inadequate grades by one of the state’s top 10 underachievers (“No problem, Dad”);

On keeping an injudicious date (“But Mother, I’ve got to see him. This is my life and you’re ruining it! You’re from the olden days. Your life is over !”);

On college education (“It is no surprise to hear a college student say on his graduation day, ‘Hopefully, I will be able to make an input. College was a fun time, but hopefully now I’ll have a viable interface with software.’ The software is his brain “).

Everybody knows, I trust, that this is all so much gruff bluff. “Fathering has changed greatly from the days when my own father used me for batting practice,” he says. The core Cosby is a would-be martinet as malleable as marshmallow. He betrays himself when on the next-to-last page he agrees that French writer Andre Malraux had it right: “Without a family, man, alone in the world, trembles with the cold.”

Warmed to the cockles by his own brood, Cosby did not wait for clearance from the trend-setters before immersing himself in the intimacies of fathering. It’s an experience he’s known firsthand from pinning diapers to pining for his daughters and sons to know happiness. This, too, needs to be said distinctly: America’s unrivaled Big Daddy, the one with the manly message, is black. He comes, from all places, out of the ranks of those American families increasingly undermined by emasculating racism and its disruptive power.

That’s surely an achievement on a number of counts, and even comic books can communicate classic truths, with or without an attending Harvard psychiatrist. Cosby’s “Fatherhood,” in short, cheerfully points in the right direction, flimsy signpost though it is.