The Half-Life of Facts

“The Half-Life of Facts: Why Everything We Know Has an Expiration Date” was released a last week. It’s dedicated to the idea that knowledge not only changes, but changes in a systematic way.

From the blurb:

Just as we know that a chunk of uranium can break down in a measurable amount of time—a radioactive half-life—so too any given field’s change in knowledge can be measured concretely. We can know when facts in aggregate are obsolete, the rate at which new facts are created, and even how facts spread. Arbesman … shows that much of what we know consists of “mesofacts”—facts that change at a middle timescale, often over a single human lifetime. Throughout, he of­fers intriguing examples about the face of knowledge: what English majors can learn from a statistical analysis of The Canterbury Tales, why it’s so hard to measure a mountain, and why so many parents still tell kids to eat their spinach because it’s rich in iron.

From Chapter 1:

But in 1956, Joe Hin Tjio and Albert Levan, two researchers working at Memorial Sloan- Kettering Cancer Center in New York and the Cancer Chromosome Laboratory in Sweden, decided to try a recently created technique for looking at cells. After counting over and over, they nearly always got only forty- six chromosomes.

Previous researchers, who Tjio and Levan spoke with after receiving their results, turned out to have been having similar problems. These other scientists had even stopped some of their work prematurely, because they could only find forty- six out of the forty- eight chromosomes that they knew had to be there. But Tjio and Levan didn’t make the same assumption. Instead, they made the bold suggestion that everyone else had been using the wrong number: There are only forty- six chromosomes in a human cell.

Facts change all the time.

I have my doubts about Arbesman’s big idea. I’m not sure how usefully one can mix concepts of scientific error (the chromosone count), unusual classification change (Pluto’s removal from planetary status), well-understood natural change (the world’s population has risen) and corporate spin (smoking won’t harm your health). It’s also slightly disturbing that Arbesman doesn’t know the boiling frog metaphor is just plain wrong. But the book is much-recommended and it’s useful to think about changes in the shape of our knowledge. You can download the first chapter here or buy it at Amazon. Sadly it seems there’s no Kindle edition yet.

About David Walker

David Walker runs editorial consultancy Shorewalker DMS (, editing and advising business and government on reports and other editorial content. Newsletter: . Among other roles, David has edited the award-winning Acuity and INTHEBLACK magazines, been chief operating officer of online publisher WorkDay Media, held senior policy and communications roles at the Committee for Economic Development of Australia and the Business Council of Australia and run the website for online finance start-up eChoice. He is a former economics writer for The Age and News Ltd. He has qualifications in law and corporate finance.
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