Ordinary people are much more adept at scientific reasoning than most psychological literature gives them credit for, argues a Cornell University expert in cognitive development in a new book.

"Most of the psychological literature that examines nonscientists' ability to reason scientifically largely ignores several principles that are crucial to scientific inquiry and that nonscientists, in fact, typically use," said Barbara Koslowski, associate professor of human development at Cornell and the author of the new book, Theory and Evidence: The Development of Scientific Reasoning (MIT Press, 1996, $40).

"Because of this, the existing literature treats as flawed reasoning that is, in fact, scientifically legitimate. As a result, most of the psychological literature provides a picture of children's and adults' ability to engage in scientific reasoning that is at best incomplete and at worst genuinely distorted," she said.

In her new book, Koslowski criticizes numerous classic studies that show that, although people seemed to behave nonscientifically, they did so precisely because they were relying on sound principles of scientific inquiry that are either not typically studied or are, mistakenly, treated as flawed. Summarizing recent studies, she argues for a different characterization of the ability of nonscientists to engage in scientific reasoning, problem-solving and reasoning about causation.

The 360-page book, intended for scholars and students of cognitive development, examines the beliefs people have about the type of evidence that counts in scientific reasoning and how those beliefs change with age. Koslowski also looks at the strategies people use in scientific inquiry, specifically, hypothesis testing and hypothesis revision when people deal with evidence that disconfirms a given explanation.

"In many situations, solving a problem or engaging in scientific reasoning amounts either to formulating or revising a causal explanation and, to do this, one must evaluate various types of evidence and/or decide which types to seek out," Koslowski explained. "What are the processes by which children and adults solve problems and the processes by which they reason about causal explanations? In this book, I argue that nonscientists reason in a scientifically legitimate way that has not yet been generally recognized by scholars in this field."

"This book will become a classic on scientific reasoning, problem solving and causal understanding. It challenges the model that dominates psychological work on these topics," said Rochel Gelman, professor of psychology at the University of California at Los Angeles.

EDITORS: For a review copy, call MIT Press at (800) 356-0343.