BOOK REVIEW / NONFICTION : A Pragmatic View of Newspapers and Life : A MATHEMATICIAN READS THE NEWSPAPER <i> by John Allen Paulos</i> , Basic Books, $18, 212 pages

Every newspaper publishes an article of pure fiction every day. It appears in the business section, and it purports to explain why the stock market went up or down the day before.

You know the one. “Stock prices rose yesterday on news of the invention of a new light bulb.” Or, alternatively, “Stock prices fell yesterday on news of the invention of a new light bulb.”

A million things happen every day, and any of them can be seized on after the fact to “explain” stock prices. No article ever says simply, “Stocks rose yesterday because more people wanted to buy than wanted to sell. The day-to-day movement of stocks is essentially random.”

No article ever says that because we insist on believing that every effect has a simple, discernible cause and we insist on finding patterns in everything, even when there are none.

This is one of the main insights of John Allen Paulos’ irreverent new book, “A Mathematician Reads the Newspaper,” the title of which is somewhat misleading. This book is not about mathematics, and it’s not really about newspapers. It should be called, “A Clear Thinker Explains the World.”

To be sure, Paulos is a professor of mathematics at Temple University in Philadelphia, and in the past he has written about mathematics for general readers. His book “Innumeracy” was a bestseller a few years ago.

But in his new book, he means “mathematician” in a broader sense: Someone who by training and temperament thinks logically and rationally. Similarly, Paulos writes here about newspapers, for which he has great affection, but he writes about them as they reflect the foibles of the world and the people who inhabit it.

This is press criticism, but not of the usual kind. (The right wing says the press is liberal; the left wing says the press is conservative.) This is press criticism of the sort that George Orwell had in mind when he observed that what’s important isn’t news, and what’s news isn’t important. As individuals and as a society, we focus on the wrong things.

Thus Paulos explains that most of the hand-wringing about environmental dangers misunderstands the nature of risk and puts too much emphasis on rare or unlikely events. “If unlimited amounts of money are spent on inconsequential hazards,” he warns, “little will be available for significant ones.”

Do cellular phones cause cancer? “It’s easier and more natural to react emotionally than it is to deal dispassionately with statistics,” Paulos writes.

This is a subversive book. Paulos argues that the world is so complex that it cannot be accurately described, much less manipulated. We always look for the cause of things, but we usually ignore coincidence as a possibility. “The real story is often as dependent on chance as on intention,” he says.

We continue to believe that there are simple explanations and that if only the right person is elected President, he or she can push the right button or pull the right lever and create jobs, feed the hungry, end crime or close the ozone hole.

In general, Paulos says, people--not just newspapers--oversimplify things that are too complicated to be understood in any case. The economy, for example. Has anyone noticed that predictions by economists are almost always wrong?

Newspapers and television come in for their share of criticism, too. Paulos is scathing in describing person-in-the-street reactions to this, that and the other thing, which he describes as “the widespread tendency to present blather and call it news.”

Paulos’ main complaint is that people are not rational. We have spent billions on the war on drugs. Paulos reports that 8,000 Americans a year die from cocaine and 6,000 a year die from heroin. By comparison, he says, 400,000 Americans die every year from smoking, and we subsidize the growing of tobacco.

Sometimes Paulos’ musings stray a bit, giving the book a certain flavor of “thoughts while shaving.” There is one interlude about the nature of self and another about the information glut: “Data, data everywhere, but not a thought to think.”

There is also some of the familiar complaint that Americans can’t do percentages and can’t see through huckster claims in advertising or politics. Here comes an insight from mathematics: “Skepticism should guide us when we read about any political, economic, or military policy of any complexity.”

This is a wise and thoughtful book, which skewers much of what everyone knows to be true. As such, it is likely to have no impact whatsoever on the way people think and the way things are done. After all, they have to fill up the newspapers with something.

Even book reviews.