Why People Buy by John O’Shaughnessy (Oxford University: $19.95; 207 pp.)

This is a textbook for professionals in consumer behavior and marketing by a professor of business at Columbia University who has worked and published extensively in the field. It should also serve small and large businessmen in addition to consumer educators, since it covers the broadest range of psychological behavior governing people’s buying habits.

It has three major limitations: It does not try to explain consumers like Tammy Bakker who go on buying sprees for psychological relief. It minimizes the probability that the public is becoming better educated in how to buy wisely; the author largely ignores such currently popular media as Consumer Reports and government publications in favor of quoting from a 1954 book that disparages research efforts by buyers. Finally, it neglects ethical issues that surely need continual restating here as much as for stockbrokers, preferably before scandals occur.

The general reader may despair, put off by an academic who writes in the tradition he quotes about Spengler’s “Decline of the West”: “. . . If a book is worth writing it is worth making it difficult to read.”

But you’ll miss good stuff if you’re put off by the often ponderous style. Skip to the end of each chapter for the concise “Summary” and “Implications for Marketing”; decide what interests you, and look back into the chapter for what you want. You’ll find much sound psychological analysis and research on a broad range of consumer behavior--state-of-the-art explanations of why people buy as they do.

You can’t merely give consumers what they want. Like clients in therapy, they often don’t know what they want. John O’Shaughnessy intends to describe “real consumers in all their glorious vagueness, illogicality and fallibility.” And he emphasizes the impact on marketing of “mainstream psychology” rather than the economists’ view of consumers as rational. He is most concerned that the book should promote a realistic but ignored approach, by “. . . recording what consumers 1935767840after buying and seek to interpret . . . (their) statements to discover the reasons and rules guiding brand choice.”

Most fun are several long statements by purchasers--by a woman buying a sewing machine, another buying a steam iron. They’re delightful descriptions of what many consumers go through that the author matches with his theories. But you might want to dodge the frequent charts. And skip long essays fleshing out such views as “In conceptually distinguishing these terms, philosophers have in the process developed . . . schemata that provide clear notions for studying intentional actions like buying.”

O’Shaughnessy is especially good at using psychological theory to describe the rational and irrational ways consumers exercise their options. He quotes a Woody Allen character who says, “The food is horrible and, what’s worse, they serve such small portions.” He’s sound in describing psychological concepts and research, the science of human behavior, such as it is, without getting into psychoanalytic obscurities.

It should be an excellent textbook for marketers, business students and consumer educators. But beyond that, with judicious selectivity, educated general readers can pick their way to facts that will give them insight into why they buy as they do. Several years ago, my kids videotaped me explaining why I had bought each of the numerous gadgets they handed me one at a time. This book covers all of my glib reasons, and many more that I didn’t think of.