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 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?

In his new book Partial Truths, Dr. James C. Zimring argues that many of the mistakes the human mind consistently makes boil down to misperceiving fractions like percentages, probabilities, frequencies, and rates.  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.

James C. Zimring has a Ph.D. in immunology and an M.D., both awarded from Emory University.  He is board certified in Clinical Pathology, a diplomate of the American Board of Pathology, and an elected member of the American Society of Clinical Investigation. He currently holds the Thomas W. Tillack chair in experimental pathology at the University of Virginia.  Dr. Zimring has maintained an N.I.H. funded laboratory for over 20 years, has published over 170 research articles, and pursues research in diseases of the blood. His previous book is What Science is and How it Really Works (Cambridge University Press, 2019).


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  • Event Date

    Wednesday, March 22, 2023

  • Start Time

    7:00 pm Pacific

  • End Time

    8:30 pm Pacific

  • Tickets


    General Admission: $25

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  • Venue

    Alberta Rose Theatre

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