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Shapiro and Newton on Experimental Philosophy

Kirsten Walsh writes…

In a recent post, I discussed Alan Shapiro’s paper, ‘Newton’s “Experimental Philosophy”‘, where he argues that

    the apparent continuity between Newton’s usage [of the term ‘experimental philosophy’] and that of the early Royal Society is, however, largely an illusion.

I examined his claim that ‘experimental philosophy’ was used as a synonym for ‘mechanical philosophy’ by the early Royal Society, whereas for Newton, the two terms had different meanings.

Today I’ll address another argument Shapiro makes in that paper.

Shapiro claims that Newton’s adoption of the experimental philosophy occurred quite late – while preparing the 2nd edition of Principia, published in 1713.  To support this claim, Shapiro argues that, in the 1713 edition of Principia, Newton uses the term ‘experimental philosophy’ for the first time in public.  Moreover, the methodology Newton describes in this context is very different to the methodology he describes in his early optical papers.  Shapiro writes:

    At this time [1675] for Newton confirmation is by mathematical demonstration and secondarily – only if you think it is worth the bother – by experiment.  He clearly believed that a mathematical deductive approach would lead to great certainty and that experiment could provide the requisite certain foundations for such a science, but until the eighteenth century he did not assign experiment a primary place in his methodology.

If Newton’s ‘experimental philosophy’ is a late development, then this provides additional support for Shapiro’s claim that Newton’s experimental philosophy is not continuous with the methodology of his predecessors, the early members of the Royal Society.

In this post, I’ll argue that (1) experiment is a prominent theme in Newton’s methodological statements between 1672 and 1713, and (2) Newton’s methodology has features that suggest the influence of the early Royal Society.

1. Experiment is a prominent theme between 1672 and 1713

There is a strong experimental theme in Newton’s early optical papers (1672-1675).  For example, he says:

    the proper Method for inquiring after the properties of things is to deduce them from Experiments.


    I drew up a series of such Experiments on designe to reduce the Theory of colours to Propositions & prove each Proposition from one or more of those Experiments by the assistance of common notions set down in the form of Definitions & Axioms in imitation of the Method by which Mathematicians are wont to prove their doctrines.


    Now the evidence by which I asserted the Propositions of colours is in the next words expressed to be from Experiments & so but Physicall: Whence the Propositions themselves can be esteemed no more then Physicall Principles of a Science.

In the opening paragraph of De Gravitatione (date of composition unknown), Newton says:

    in order, moreover, that … the certainty of its principles perhaps be confirmed, I shall not be reluctant to illustrate the propositions abundantly from experiments as well…

In the 1st edition of Principia (1686), Newton says:

    The principles I have set forth are accepted by mathematicians and confirmed by experiments of many kinds.

And in the 1st edition of Opticks (1704), Newton says:

    My Design in this Book is not to explain the Properties of Light by Hypotheses, but to propose and prove them by Reason and Experiments…

Experiment doesn’t seem secondary to me!

2. Newton’s methodology suggests the influence of the early Royal Society

As we have said before, the Royal Society adopted the experimental philosophy in a Baconian form – according to the Baconian method of natural history.  There is good evidence that Newton was familiar with the work of the Royal Society by the time he wrote his first optical paper in 1672: his notebooks show that he took notes from many issues of the Philosophical Transactions and he took careful notes on Boyle’s work.  Newton never adopted the Baconian method of natural history.  However, other features of Newton’s methodology suggest the influence of the early Royal Society.  For example, he made use of queries, he adopted the familiar distinction between theory and hypothesis, he was concerned with experiments, and he rejected speculation and speculative systems.

Shapiro notices that Newton rejected speculative systems, but fails to recognise that Newton wasn’t the first member of the Royal Society to take this stance.  On this blog we have provided ample evidence that the early members of the Royal Society railed against speculation.  Newton’s anti-speculation and anti-hypothetical stance, while extreme, was still inside the spectrum of acceptable experimental positions.  Consider this passage from Hooke’s Micrographa, addressed to the Royal Society:

    The Rules YOU have prescrib’d YOUR selves in YOUR Philosophical Progress do seem the best that have ever yet been practis’d.  And particularly that of avoiding Dogmatizing, and the espousal of any Hypothesis not sufficiently grounded and confirm’d by Experiments.  This way seems the most excellent, and may preserve both Philosophy and Natural History from its former Corruptions.

Whether or not Newton explicitly identified himself as such, we have good reason to think that Newton’s first optical paper in 1672 was written by an experimental philosopher.

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