Book review: 'The Half-Life of Facts' by Samuel Arbesman

PUBLISHED : Sunday, 25 November, 2012, 12:00am
UPDATED : Monday, 03 December, 2012, 4:09pm

The Half-life of Facts: Why Everything We Know Has An Expiration Date
by Samuel Arbesman

Although we generally tend to consider facts as objective truths, many types of facts are actually in flux. Facts change when scientists make new discoveries, or when errors are corrected, for instance.

The Half-life of Facts analyses how facts change, the rate at which they change, and what this means for our everyday lives.

Epistemology is a branch of philosophy that deals with knowledge - what we know, what we can know, and how we know it. But Samuel Arbesman, who is not schooled in philosophy, steers clear of this approach. Instead, he sticks to what he understands: statistics, and how they can be usefully applied. The author's big idea is to mine the available data and literature on scientific advances to construct a model of the speed of change. If we know how fast things change, he thinks, we will not be surprised by new developments.

His results are interesting. The sum total of knowledge in the field of medicine and hygiene takes 87 years to double, mathematics takes 63 years, and chemistry only 35. Physics textbooks become outdated after 13.07 years, maths textbooks last 9.17 years, and history books only last 7.13 years. It's important to be aware of this, says the author, as it prepares us for new things, and prods us to keep our thinking up to date.

A portion of the book looks at how facts are spread, and how they are accidentally changed to become inaccurate in the process. Although Arbesman refers to facts, he is writing more about the wider subject of information here. This was dealt with in great detail in James Gleick's fascinating 500-page tome The Information last year.

Arbesman goes over some of the same topics, but his approach adds detail in some areas. He describes the frequency that scribes who copied hand-written books made errors, for instance, so that the accuracy of a copied work can be assessed by knowing how many copies came between it and the original.

Facts are a difficult business. Some aspects of them can only be properly studied in the realm of philosophy. For instance, the differences between a fact and a truth, along with the nature of truth itself, are still debated on philosophy courses. A branch called philosophy of science examines the theoretical limits of scientific knowledge. Theoretical physics plays a part, too, as that deals with how time works. And psychology and neuroscience weigh in on the subject with their investigations into memory and perception.

Arbesman's statistically based approach to the subject is a clear-headed addition to the debate.