Dr. James Zimring

Partial Truths

How Fractions Distort Our Thinking

A fast-food chain once tried to compete with McDonald’s quarter-pounder by introducing a third-pound hamburger—only for it to flop when consumers thought a third-pound was less than a quarter-pound because three is less than four. Separately, a rash of suicides by teenagers who played Dungeons and Dragons caused a panic in parents and the media in the U.S. They thought D&D was causing teenage suicides—when in fact teenage D&D players committed suicide at a much lower rate than the national average. Errors of this type can be found from antiquity to the present, from the Peloponnesian War to the COVID-19 pandemic. How and why do we keep falling into these traps?

James C. Zimring argues that many of the mistakes that the human mind consistently makes boil down to misperceiving fractions. We see slews of statistics that are essentially fractions, such as percentages, probabilities, frequencies, and rates, and we tend to misinterpret them. Sometimes bad actors manipulate us by cherry-picking data or distorting how information is presented; other times, sloppy communicators inadvertently mislead us. In many cases, we fool ourselves and have only our own minds to blame. Zimring also explores the counterintuitive reason that these flaws might benefit us, demonstrating that individual error can be highly advantageous to problem solving by groups. Blending key scientific research in cognitive psychology with accessible real-life examples, Partial Truths helps readers spot the fallacies lurking in everyday information, from politics to the criminal justice system, from religion to science, from business strategies to New Age culture.


In this brilliant follow up to What Science Is and How It Really Works, James Zimring engages the reader in a kind of detective story about the classic mistakes of human reasoning, due to our innumeracy. From bad social policy to pandemics to terrorism, he shows how human decision making often gets it so wrong. What I loved most about Partial Truths though is that he didn't just establish that we make errors, but why. This amounts to a handy, insightful, eminently readable guide to the intricate evolution of the human mind itself. If you enjoyed Daniel Kahneman's Thinking Fast and Slow, you'll love this book.

Lee McIntyre, author of How to Talk to a Science Denier


Using the simple notion of a fraction as a lens, James Zimring insightfully discusses a remarkable variety of issues from cognitive psychology to New Age beliefs to misunderstandings in politics. Thoughtful and wide-ranging.

John Allen Paulos is a Professor of Mathematics at Temple University and the national bestselling author of Innumeracy:Mathematical Illiteracy and its Consequences and also A Mathematician Reads the Newspaper


Numbers become far more than abstractions in the capable hands of James Zimring. I learned something fascinating and enlightening on nearly every page of Partial Truths – about politics, social policy, economics, cultural choices, criminal justice, and much more.

Steven Lubet, author of Interrogating Ethnography: Why Evidence Matters


In Partial Truths Zimring offers an entertaining and illuminating look at how we all misunderstand –– and how the media and politicians misrepresent, and even scientists sometimes distort –– the numbers and data that underlie so much of our conventional wisdom.

David Zweig, Author of Invisibles: The Power of Anonymous Work in an Age of Relentless Self-Promotion.


James Zimring’s new book, Partial Truths, takes a walk through the various ways human cognition fails when dealing with numbers, probabilities, risk, and assessing evidence. Along the way Zimring takes us through a bestiary of fascinating case studies both historical and modern. His clear prose illuminates the ways that politicians take advantage of our cognitive shortcomings, the ways that numbers mislead us in everyday life, and what this means for important social topics like racialized criminal justice, war mongering, and public belief in science. A great book for those grappling with the confusion of our modern information environments.

Cailin O'Connor, Author of The Misinformation Age: How False Beliefs Spread


Zimring does a great job breaking down complex theories of statistics and mathematical equations into relatable stories and examples. His perception… is fascinating.

Austin Katz, AIPT Review