Gardner deflates some scientific charlatanism; Science Good, Bad and Bogus, by Martin Gardner. Buffalo, N.Y.: Prometheus Books. $18.95.

Martin Gardner, everybody's favorite mathematical puzzle spinner, has not been so popular when it comes to extrasensory perception, flying saucers, and other pseudoscientific fancies. In fact, he has been a ''true believer's'' bete noire.

Good for him! A comment like that undoubtedly shows my own bias in such matters. Nevertheless, and with one reservation, I think this collection of his skeptical writings is a good antidote for the flood of pseudoscientific pap that continues to wash through the media.

Gardner has collected a number of his essays written over the past three dacades. To most of these, he has added postscripts indicating where he thinks he was right and where he was wrong and how the subject has developed since he wrote about it. Both the originals and the postscripts are pungent, incisive, and witty, which brings up my reservation.

Gardner is a member of a highly useful volunteer group known as the Committee for Scientific Investigation of Claims of the Paranormal (CSICP). Both the committee generally, and Gardner particularly, make a valuable contribution to society in debunking pseudoscientific frauds and delusions through careful investigation. However, the disgust committee members feel for such things too often colors their comments, including articles in the otherwise excellent little journal The Skeptical Inquirer, which CSICP publishes. This introduces an intemperate tone which undercuts its credibility and, unfortunately, mars Gardner's book.

This is only a minor drawback, however, in what is otherwise an entertaining and instructive volume.

Gardner dissects a number of popular fallacies, including the exploits of spoon-bender Uri Geller. In fact, it's unfortunate that the book has no index to help readers refer back to one of the many subjects. Also, while most of the essays deal with pseudoscience, a few tilt their lances against what Gardner considers to be exaggerated or distorted popularization of straight science. Here Carl Sagan, among others, takes a drubbing.

In short, Gardner shines a light of reason on a variety of fallacies, adhering to his dictum that the best antidote for nonsense is often just a good horse laugh. It is a book to be dipped into and enjoyed, but not if you fancy the cosmology of Emmanuel Velikovsky or share Arthur Conan Doyle's belief in the ''wee people."