# How Newton thought of the law of gravitation according to Newton

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I got this Newton quote out of Richard Westfall's book -Never at Rest- which is a thorough well researched biography of Newton and an accounting of the stages of thought that Newton went through. In Newton's letter to Bentley 10 Dec 1692, Newton wrote "But if I have do the public any service this way 'tis due to nothing but industry and patient thought". (Sounds like Edison, doesn't it?). This was retold by Voltaire (who was a Newton fan) later as "By thinking on it continually" this was Voltaire's version of Newtons's reply to the question of how he finally got the law of gravitation (the famous inverse square law).

In none of the documents written by or about Newton, did Newton every refer to the notion of first level concepts. What he did do was to conclude after long period of investigation and cogitation that the two manifestations of gravitation he studied a) the falling of objects near earth and the motion of the moon about earth which he later realized was a falling motion. This he elaborated in the motion of Jupiter's moons which were finally understood as a falling around the planet Jupiter. This was later generalized to all bodies.

One could argue that falling is a first level concept, but Newton's first crack at gravitation was by way of a balance between centrifugal force and centripital force (think of how a rock spinning around held by a string manifests that balance). Later at Robert Hooke's suggestion Newton saw the path of falling bodies around the earth and the sun as the resultant of two forces. One the centripital force caused by the attraction of a central body and the second the inherent force of inertia ( vis insita). In short the key to Newton's law as embodied in his proof of the Law of Equal Times (Kepler's Law) was inertia which is NOT a first level concept. It is an abstraction gained after much study and idealized thought. Nowhere in the world is there a body totally free of any force so that it would either remain at (relative) rest or move in a straight line at constant velocity.* In fact the idea of an inward pulling force not mediated by any physical contact was repugnant to Newton and most other thinkers in Newton's time. It smacked of voodoo and magic, force at a distance. Newton settled on the famous inverse square law through mathematical compulsion and he never settled on any hypothetical causes of gravitation. In short, Newton did not know why things fell, but he had a mathematically sound description of their falling. If anything centripital force ran square against common sense and first order concepts. When did a kid ever see a clearly given force (in his limited experience) that was NOT a contact force? All kids grab and push things. Pushes and pulls are first order concepts, but they require contact.

Just a comment here. Which is a better source for finding out how master scientists and natural philosophers came by their ideas? Going directly to the source, or consulting L.P. and Ayn Rand on concepts?

I am doing thorough research on Newton, Galileo and Maxwell by going right back to original sources or correspondence of people with whom the masters were in contact. As it says in Scripture: Look unto the rock from which you were hewn. This will take a bit of time so my review of Harriman's book must await my studies of Newton, Galileo, Maxwell and other real scientists and thinkers.

Ba'al Chatzaf

*Aristotle never figured inertia because the world he lived in was highly frictional. All forced motions ceased when the force was removed. It was not until 800 or 900 years after Aristotle that the notion of impetus was conceived, a partial step toward momentum and inertial. See the works of John Philliponus circa 650 C.E. We did not have a proper basis for mechanics until inertia was clearly conceived and its consequences worked out mathematically.

Edited by BaalChatzaf
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Which is a better source for finding out how master scientists and natural philosophers came by their ideas? Going directly to the source, or consulting L.P. and Ayn Rand on concepts?

Much of Harriman's book is about the former.

I am doing thorough research on Newton, Galileo and Maxwell by going right back to original sources or correspondence of people with whom the masters were in contact. As it says in Scripture: Look unto the rock from which you were hewn. This will take a bit of time so my review of Harriman's book must await my studies of Newton, Galileo, Maxwell and other real scientists and thinkers.

That was Harriman's approach, too. You can learn that in about 20 minutes by listening here.

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Which is a better source for finding out how master scientists and natural philosophers came by their ideas? Going directly to the source, or consulting L.P. and Ayn Rand on concepts?

Much of Harriman's book is about the former.

I am doing thorough research on Newton, Galileo and Maxwell by going right back to original sources or correspondence of people with whom the masters were in contact. As it says in Scripture: Look unto the rock from which you were hewn. This will take a bit of time so my review of Harriman's book must await my studies of Newton, Galileo, Maxwell and other real scientists and thinkers.

That was Harriman's approach, too. You can learn that in about 20 minutes by listening here.

That was the Grok broadcast. Been there, done that. I find Harriiman is superficial in his knowledge of Newton and Galileo. Also his notion of first order concepts really do not explain very well what Newton and Galileo (and Kepler and Maxwell) did. I am currently underwhelmed by the pop-psych of L.P. and A.R.

Ba'al Chatzaf

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That was the Grok broadcast. Been there, done that. I find Harriiman is superficial in his knowledge of Newton and Galileo. Also his notion of first order concepts really do not explain very well what Newton and Galileo (and Kepler and Maxwell) did. I am currently underwhelmed by the pop-psych of L.P. and A.R.

Harriman did not claim that first-level concepts explain what Newton and the others did. I am currently underwhelmed by your superficial knowledge of what Harriman's book says.

First-level concepts based on perception support generalizations including induction in two ways. The first is the cognitive growth of a child. The second is reduction -- tracing higher-level concepts and generalizations back to perception.

Edited by Merlin Jetton
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That was the Grok broadcast. Been there, done that. I find Harriiman is superficial in his knowledge of Newton and Galileo. Also his notion of first order concepts really do not explain very well what Newton and Galileo (and Kepler and Maxwell) did. I am currently underwhelmed by the pop-psych of L.P. and A.R.

Harriman did not claim that first-level concepts explain what Newton and the others did. I am currently underwhelmed by your superficial knowledge of what Harriman's book says.

When I get to it I will read every word twice or three times. It will be thoroughly combed for fleas. I intend to document everyone of my critical remarks using original or first rate derivative sources on Galileo, Kepler, Newton and Maxwell. As I said, to find out what the masters did, one goes to the masters. For Newton, in addition to Westfall's biography, the works of I. Bernard Cohen is a first rate treasure trove. He has translated Principia and De Motu into modern English and made plain Newton's mathematical methodology. Much of what Newton did (and he declared it himself) was mathematically driven. Newton's understanding of Gravity was as un commonsensical in terms of what was acceptable in his day as quantum mechanics is now.

It turned out the commonsense theory of gravitation as given by Descartes was dead wrong (based on ether vortices). Newton demolished Descartes in Book 2.

Ba'al Chatzaf

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I intend to document everyone of my critical remarks using original or first rate derivative sources on Galileo, Kepler, Newton and Maxwell.

Do you intend to document any favorable remarks?

Edited by Merlin Jetton
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I intend to document everyone of my critical remarks using original or first rate derivative sources on Galileo, Kepler, Newton and Maxwell.

Do you intend to document any favorable remarks?

Everything I write will be documented against original sources and first rate derivative sources.

Ba'al Chatzaf

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I intend to document everyone of my critical remarks using original or first rate derivative sources on Galileo, Kepler, Newton and Maxwell.

Do you intend to document any favorable remarks?

Everything I write will be documented against original sources and first rate derivative sources.

You didn't answer my question at all.

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I intend to document everyone of my critical remarks using original or first rate derivative sources on Galileo, Kepler, Newton and Maxwell.

Do you intend to document any favorable remarks?

Everything I write will be documented against original sources and first rate derivative sources.

You didn't answer my question at all.

If I see anything favorable I will say so and document why I said so.

Ba'al Chatzaf

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