DURING A STINT of teaching a basic course in philosophy, a decade ago, I searched in vain for a book that would provide a true introduction for inquiring minds. With a few reservations, Martin Gardner's The Whys of a Philosophical Scrivener may be the answer.

For many people, philosophy presents an alluring but formidable facade. While the word means "a love of knowledge," the subject confronts the amateur with such mind- boggling terms as ontology, metaphysics, and transcendence. Gardner removes the mystery from these expressions. He explains ontology as the study of being, or that which is; metaphysics as a probing into the principles that lie behind the make-up of the cosmos; and transcendence as the bridge from the material universe to the "wholly other," or the realm of spirit.

Gardner begins The Whys of a Philsophical Scrivener with a discussion of solipsism (from the Latin soli ipsi, "to myself alone"). This is the thesis that what I seem to see, hear, touch, taste, and observe exists only in my mind, is a figment of my imagination. Strangely enough, it is an aberration that has attracted a surprising array of thinkers.

Accepting his own cosmic existence, Gardner next involves the reader in problems with which human awareness is concerned. He deals with the nature of truth in its epistemological--how do I know that I know?--dimension. After an excursion into economics and politics, anarchism and communism, he pushes on to an appreciation of beauty and goodness. Then he tackles the problem of evil with particular vigor, discussing the possibility that the personal evil that one does here and now is not only of one's own damned willfulness, but in some unfathomable fashion, reflects a divine plan for the governance of the universe.

This notion involves him in arguments with atheists, agnostics, fundamentalists, theists, and believers as he probes the possibility of immortality, both Cicero's non omnis moriar--not all of me will die, thanks to my literary works --and St. Paul's seeing God facie ad faciem, face to face. Having eliminated hell, he finds value in prayer, the inner dialogue we entertain with ourselves and the unfathomable with whom we talk when in danger or dismay.

Among the hundreds of authors he cites, Gardner professes a particular affinity for two modern publicists-- the bizarre Catholic, G.K. Chesterton and the atheist H.G. Wells, with neither of whom he agrees in the long run. He admires them for their constant capacity for wonder.

Professing himself a theist, Gardner yet proves a severe critic of the Christian creed and its scriptural, anthropomorphic concept of God. He thus joins a long line of anti- Christian adversaries from Plutarch and Celsus in the second century to Robert Ingersoll and Bertrand Russell in the 20th. In so doing he perpetuates the myth that there is an inevitable war between science and religion.

Actually both religion and science have only the tools of logic with which to gauge the validity of the phenomena they evaluate. Using different methods, they are equally open to rational explanation as well as superstition, fraud, and wishful thinking.

While authentic science deals with the material world and thus seems better anchored in fact, authentic religion wrestles with the spirit and is thus more exposed to the vagaries of fancy. But if each discipline sticks to its last, there need be no quarrel between them.

In the final analysis, Gardner presents us with a theodicy. In Leibniz's definition, this is a justification for the existence of a personal God, one under whose aegis Gardner discusses "everything knowable and a few other items besides." He confronts the reader with a whirlwind of quotations, poetic effusions, and the paraphernalia of learned as well as pedestrian discourse.

Mercifully the book ends with a full-blown index allowing the absent-minded reader the luxury of rediscovering favorite quotes, bits of verse and, discussions that struck his fancy. All in all, reading Gardner's The Whys of a Philosophical Scrivener is a delightful and instructive experience.