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THE PLURAL OF THE WORD “Histories” sets Mahoney’s book apart from other attempts of putting computers in historical perspective. Published in 2011, the book was assembled by Thomas Haigh following Mahoney’s death at the age of 69 in 2008. It’s a daunting yet fascinating look at its subject and at the idea of history per se. Here are tidbits gleaned thus far from my reading Haigh’s Introduction and a couple of Mahoney’s thoughtful essays. 

Histories of Computing, by Michael Sean Mahoney, edited by Thomas Haigh, Harvard Press, 2011

On Reading Principia Mathematica. Mike Mahoney earned a Ph.D. in history and history of science at Princeton in 1967 and taught there for more than forty years. 

Michael Sean Mahoney, 1939–2008, American historian of science. Image from

In their JSTOR article, former students Jed Z. Buchwald and D. Graham Burnett recalled two full generations of undergraduates who “retain gulp-inducing memories of his drop-this-class-if-you-don’t-want-to-sweat opening lecture in History 291, his class on the Scientific Revolution.”

Mahoney was a skilled reader of sixteenth-century Latin. What’s more, he “had deep familiarity with the mathematic notation and scientific practice of the period…. He was prone to lament that few students today could read Newton’s Principia Mathematica in the original.” Evidently Mahoney gained historical insights from doing so.

What Makes History? Mahoney said to students of the subject, “After all, you’ve been talking about the past, you’ve got the events and people in chronological order, you’ve related what’s happening. What more could be needed to make history?”

He suggested, “It’s a matter of going back to the sources, of reading them in their own language, and of thinking one’s way back into the problems and solutions as they looked at them.” 

On Documentation. Mahoney gives an example: “Several years ago I asked someone at Bell Labs responsible for maintaining software what sort of documentation she would like most to have but did not. ‘I’d like to know why people didn’t do things,’ she said. ‘In many cases when a problem arises, we look at the program and think we see another, better way of doing things. We spend six months pursuing that alternative only to discover that it won’t work, and we then realize why the original team didn’t choose it. We’d like to know that from the start.’ ”

“Something quite close to that,” Mahoney said, “holds for historians too. They want to know what the choices and possibilities were at a given time, why a particular one was adopted, and why the others were not. Good history, from a historian’s point of view, always keeps the options in view at any given time.” 

The Ptolemy Model. As an example, recall the Ptolemy model of geocentric astronomy, that everything revolves around the Earth. This theory reigned from 140 A.D. until Copernicus (not without stern churchly objection) in 1543.

A crowned Ptolemy being guided by Urania, from a 1508 engraving. 

In his History 291, as noted by Buchwald and Burnett, “… using a computer program of his own confection, he demonstrated the intricacies of the Ptolemaic cosmography, complete with dizzying loops upon loops of epicycles, eccentric deferent, and a speckling of equant points.”

“The lesson,” the authors write, “was twofold: First, history of science was going to require that everyone gird up for problem sets; second, superseded explanations of natural phenomena might indeed have been wrong, but they were finely wrought things.” 

I look forward to learning more of Mahoney’s lessons. ds 

© Dennis Simanaitis,, 2022 

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