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Dr. David Harriman Faces His Critics

November 18, 2010

A few weeks after an unlikely critic published his controversial review on, Dr. David Harriman, physicist and Objectivist author of a monumental book titled The Logical Leap: Induction in Physics, finally faced his critics, saying that “in a very important sense, he was “innocent” of the accusation that he presented an a “unconventional” history of science.

Harriman’s most important book was endorsed by his teacher, Dr. Leonard Peikoff, legal and intellectual heir of philosopher Ayn Rand. Peikoff wrote the book’s introduction.

On September 4, Dr. John P. McCaskey, who resigned from the Board of Directors of both the Ayn Rand Institute (ARI) and the Anthem Foundation for Objectivist Scholarship, published a contentious review of Dr. Harriman’s book on titled Potentially seminal theory, but some unconventional history.

McCaskey’s review opens with the following sentence: “Readers of the book should be aware that the historical accounts presented here often differ from those given by academic researchers working on the history of science and often by the scientists themselves.” He gave Harriman’s book the neutral three-star rating.

McCaskey wrote:

Harriman, for example, recounts how Galileo determined that “the rate at which a body falls is independent of its weight.”

“Galileo demonstrated the answer with his characteristic flair. He climbed to the top of the famous Leaning Tower and, from a height of more than fifty meters, dropped two lead balls that differed greatly in size and weight. The students and professors assembled below saw both objects hit the ground at very nearly the same time. . . . Galileo then asked the next logical question: Does the rate of fall depend upon the material of the body? He repeated the experiment using one ball of lead and another made of oak. Again, when dropped simultaneously from a great height, they both hit the ground at very nearly the same time. Thus Galileo arrived at a very broad generalization: All free bodies, regardless of differences in weight and material, fall to Earth at the same rate.” (p. 43)

Harriman rightly observes that this “seems too easy. It appears as though Galileo arrived at this fundamental truth . . . merely by doing a few experiments that any child could perform.” But, Harriman explains, Galileo’s breakthrough was not the experiments per se but the application of a concept that had eluded his predecessors, the concept of friction. That is, Galileo arrived at his law by carefully accounting for air friction in the Leaning Tower experiment.

This is not, however, the account that Galileo himself gives. Harriman writes, “Imagine that he attempted to drop the lead or oak balls through water instead of air . . . . The result would not have led to any important discovery.” But in the Discorsi Galileo presents the difference between dropping balls through air and dropping them through water as the very heart of his discovery. (Day One, 8:110-116). He begins by recounting a report of the tower experiment but does not consider it sufficient to establish the law. He instead explains that we must consider air as a medium and compare what happens in other mediums, such as water and mercury. He notes that heavier things (ones heavy enough not to float) do land at different times and the difference is bigger the higher the resistance of the medium. In water the difference is higher than in air; in mercury, the difference even higher. Galileo extrapolates and concludes that in a medium that offered no resistance, there would be no difference in speed of fall and all objects would hit at the same time. Galileo claimed that comparing the dropping of objects in air, in water, and in mercury is exactly what justifies his discovery, contra Harriman’s claim.

Now let me post Dr. Harriman’s answer to McCaskey and his critics titled Is My Account of History “Unconventional”?:

Now, I will begin to face my critics.

I have been accused of presenting an “unconventional” history of science. Apparently, to depart from convention is a serious crime. How do I plead? Am I guilty or innocent?

In a very important sense, I confess to being innocent. My book does not contain any new discoveries in the history of science. What I say about the discoveries of great scientists can be found in the writings of the scientists themselves or in the writings of the best historians of science (see the references at the end of the book). For example, my account of Galileo’s discoveries relies heavily on the work of Stillman Drake, whom I regard as the best of the Galileo scholars. There was a time when Drake’s view of Galileo was very “unconventional”; most historians regarded Galileo as a Platonist who arrived at conclusions by thought experiments and mathematical deduction, whereas Drake showed that Galileo was a brilliant experimentalist. Scholars such as Drake conduct painstaking investigations to discover previously unknown facts about what scientists actually did. This is not the type of work I do, so I rely on those who do it.

In another sense, however, I am proud to be guilty as charged. My account of the history is unconventional because I have condensed an enormous amount of material in order to reveal the essential logic of the discovery process. For example, starting from more than 2,000 pages of material written by Galileo himself, or by Drake and other historians, I boiled it down to a 20 page section of my book that focuses on the crucial discoveries and the method that led to them. By today’s standards, this is unconventional; any essentialized account is typically dismissed as simplistic. Contemporary academics suffer from a disease that can be characterized as “complexity worship.” As a result, they bury the important points under mountains of trivia. I have tried to sift through the details and clear most of them away—in order to reveal the buried treasures.

At times, this ruthless process of essentializing forced me to make painful decisions. For example, I omitted discussion of Newton’s famous “rings” experiment, in which he associated a wavelength with each color of light. This is one of the most brilliant experiments of the 17th century, and a personal favorite of mine. But it was not absolutely necessary for what I needed to say about Newton’s theory of colors, so I cut it out.

On the other hand, I sometimes included experiments that are omitted in most other historical accounts. For example, I included an experiment that Newton himself left out of his Optics book—the one where he looked through a prism at a thread painted half blue and half red. In this case, I judged the experiment to be essential to the logic of his discovery process. Another case can be found in Chapter 5 on atomic theory: most historians omit the discovery of ozone, but I think it is crucial because it refuted a major objection to Avogadro’s law.

In every case, my selection criterion was the same: Is a particular point or experiment absolutely necessary to arrive at the generalization I am trying to reach? My selection criterion was not: What do most other historians usually say?


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