LET ME COMMENCE with a statement of policy. It's my belief that book reviewers ought to have the same rights and privileges enjoyed by movie, theater and television critics. You can walk out of a lousy movie or play, turn off a godawful television show. I am still haunted, after many years, by the memory of what a reviewer friend of mine suffered through because he'd vowed to read every page of Atlas Shrugged before he wrote about it. I promised myself, way back then, that nothing like that would ever happen to me. There's no reason for not openly admitting which of the books under consideration I walked out on, which is what I'll be doing. DARK IS THE SUN. By Philip Jose Farmer. Del Rey/Ballantine. 405 pp. $9.95

Talk about the far future, this one takes place 15 billion years hence -- a time few of us will live to see, when the earth is a waning and primitive place. Society is pretty much the way it was in cave days. Things are so bad intellectually that people have taken to spelling Jim as Jum and our hero, Dave, goes around tagged Deyv. Obviously here is a culture badly in need of a proofreader. Always fond of the odyssey format, Farmer uses it here once again as Deyv roams the dying earth looking for his Soul Egg. I assume he finds the thing somewhere between pages 21 and 405, since when I sneaked a look at the finish, everyone was quite joyful.

Probably part of my antipathy to this sort of book is triggered by nothing more than the fact I still sometimes move my lips when I read. I'm therefore more annoyed than enthralled at stumbling across names and words such as "Agorn," "veushmikl," "fookooki," "athaksum," "Aejip" and "ujusmikl." If, however, this is just the sort of mumbo jumbo that weaves a spell for you, carrying you off on the wings of lusty adventure, then try Farmer. He does this sort of book about as well as anyone can. AMBULANCE SHIP. By James White. Ballantine. 184 pp. $1.95

Here's the latest in White's long-running series about medics in space. White is fascinated not only with the future course of the medical profession but with the particulars of alien life. His human characters work with a wild variety of other types, including folks with six multi-jointed legs and ones with cylindrical bodies covered with silvery fur. The major problem this time is a puzzling epidemic, and White does a good job of juggling space hardware, medical lore and alien speculation. PLANET STORY. By Harry Harrison. Illustrated by Jim Burns. A & W Visual Library. 113 pp. $10.95

Harry Harrison has written some hilarious of novels in his day and there's no reason, or hardly any, not to believe he'll get another hit next time at bat. The biographical note mentions his fondness for the pubs of Ireland, the country where he now resides. You get the impression after not too much exposure to this space-opera burlesque that it must have been composed in Harrison's favorite pub. You wonder how he managed to get the men's room wall over to the printer's. I suppose it's possible, in this Belushi Era, that some will be moved to fits of laughter by a book whose hero is named Private Parrts. Wait, wait, you haven't heard the name of the central woman character. It's Styreen Fome.

The book is profusely illustrated by Jim Burns, and I do mean profusely. He's apparently stared at Maxfield Parish so long he's done himself permanent taste damage. THE UNLIMITED DREAM COMPANY. By J. G. Ballard, Holt, Rinehart and Winston. 238 pp. $10.95

Have you ever felt the people who give away the quotes for the back of dust jackets might possibly be different from you and me? Their threshold of pleasure appears to be much lower, they are highly excitable, and when you give them a heavy potential bestseller, they find they can't put it down. I was unsettled by Anthony Burgess' over-reaction on the rear of this book. "This idea is blindingly original," he exclaims. My eyesight isn't all that good already, so I was a bit reluctant to risk losing the rest of it over another of Ballard's ponderous allegories. Eventually I decided I had to make the attempt. I'm able to report you can read this, at least up to page 54 where I bailed out, with no great physical risk.

To me Ballard's prose is flat and humorless. I soon found myself nursing the suspicion that I wasn't struggling through a profound commentary on the innermost meanings of life and death, but rather just another flat-footed novel about an uninteresting young chap with not much to say. This particular uninteresting young chap crashes his stolen helicopter in Shepperton, England, gets involved with a collection of people who are even more uninteresting than he and eventually learns to fly like a bird. WINDOWS. By D. G. Compton. Berkley/Putnam. 255 pp. $10.95

I used to have a beard and Compton, judging by his photo, still does. These somewhat personal facts are mentioned to explain why I quietly exited this one at page 16. That's when I encountered these lines:

"She'd existed without him for so long. Grasping the close, rough hair of his beard, she drew his mouth down upon her own. And lost her awareness of self entirely."

Even in a near future world as grim and sober-sided as the one Compton operates in, when someone tugs your beard hard enough to yank your head down into kissing range, you're going to say, "Ouch!" or, "I say, old girl, I rather wish you wouldn't do that."

Judging by the opening pages and the helpful blurb, the hero of this book, when he isn't standing around having his beard jerked, has been making a living as a human television camera. He's had a miniaturized, let us hope, TV camera implanted in his skull and his eyes serve as the lenses. But instead of enjoying his position as the ultimate newsperson, Rod comes down with one of those bad cases of how-dreadful-it-all-is which inflict people in Compton's works. To demonstrate his dissatisfaction with his work, Rod blinds himself.

It could be there's some intended symbolism in all this that I'm missing.