1. How does Newton's method compare with those of Bacon and Descartes? with those of ancient and medieval scientists?
2. What does rule four imply about certainty of scientific propositions?
3. Why does Newton refuse to "frame a hypothesis"?
We are to admit no more causes of natural things, than such as are both true and sufficient to explain their appearances.
To this purpose the philosophers say, that Nature does nothing
in vain, and more is in vain, when less will serve; for Nature
is pleased with simplicity, and affects not the pomp of superfluous
Therefore to the same natural effects we must, as far as possible, assign the same causes.
As to respiration in a man, and in a beast; the descent of stones
in Europe and in America; the light of`our culinary fire and of
the sun; the reflection of light in the earth, and in the planets
The qualities of bodies, which admit neither intension nor remission of degrees, and which are found to belong to all bodies within reach of our experiments, are to be esteemed the universal qualities of all bodies whatsoever.
For since the qualities of bodies are only known to us by experiments,
we are to hold for universal, all such as universally agree with
experiments; and such as are not liable to diminution, can never
be quite taken away. We are certainly not to relinquish the evidence
of experiments for the sake of dreams and vain fictions of our
own devising; nor are we to recede from the analogy of Nature,
which is wont to be simple, and always consonant to itself. . . .
In experimental philosophy we are to look upon propositions collected by general induction from phenomena as accurately or very nearly true, notwithstanding any contrary hypotheses that may be imagined, till such time as other phenomena occur, by which they may either be made more accurate, or liable to exceptions.
This rule we must follow that the argument of induction may not
be evaded by hypotheses.
Hitherto we have explained the phenomena of the heavens and of our sea by the power of gravity, but have not yet assigned the cause of this power. This is certain, that it must proceed from a cause that penetrates to the very centers of the sun and planets, without suffering the least diminution of its force; that operates not according to the quantity of the surfaces of the particles upon which it acts (as mechanical causes used to do), but according to the quantity of the solid matter which they contain, and propagates its virtue on all sides to immense distances, decreasing always as the inverse square of the distances. Gravitation towards the sun is made up out of the gravitations towards the several particles of which the body of the sun is composed; and in receding from the sun decreases accurately as the inverse square of the distances as far as the orbit of Saturn, as evidently appears from the quiescence of the aphelion of the planets; nay, and even to the remotest aphelion of the comets, if those aphelions are also quiescent.
But hitherto I have not been able to discover the cause of those properties of gravity from phenomena, and I frame no hypotheses; for whatever is not deduced from the phenomena is to be called an hypothesis; and hypotheses, whether metaphysical or physical, whether of occult qualities or mechanical, have no place in experimental philosophy. In this philosophy particular propositions are inferred from the phenomena, and afterwards rendered general by induction. Thus it was that the impenetrability, the mobility, and the impulsive force of bodies, and the laws of motion and of gravitation, were discovered. And to us it is enough that gravity foes really exist, and act according to the laws which we have explained, and abundantly serves to account for all the motions of the celestial bodies, and of our sea.
Isaac Newton, The Mathematical Principles of Natural Philosophy,
trans. A. Motte (London, 1729). [Capitalization and spelling
have been modernized.]
This text is part of the Internet Modern History Sourcebook.
The Sourcebook is a collection of public domain and copy-permitted
texts for introductory level classes in modern European and World
Unless otherwise indicated the specific electronic form of the
document is copyright. Permission is granted for electronic copying,
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(c)Paul Halsall Aug 1997
This text is part of the Internet Modern History Sourcebook. The Sourcebook is a collection of public domain and copy-permitted texts for introductory level classes in modern European and World history.
Unless otherwise indicated the specific electronic form of the document is copyright. Permission is granted for electronic copying, distribution in print form for educational purposes and personal use. If you do reduplicate the document, indicate the source. No permission is granted for commercial use of the Sourcebook.
(c)Paul Halsall Aug 1997