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Monthly Archives: April 2015

Experimental Philosophy and Mechanical Philosophy II: The Case of Robert Boyle

Peter Anstey writes …

What is the precise relation between experimental philosophy and mechanical philosophy in the seventeenth century? In my last post I showed how neither Henry More nor Henry Stubbe were particularly clear about this. In this post I examine the view of Robert Boyle.

Boyle is sometimes credited with coining the English term ‘mechanical philosophy’* and he was certainly the first person to use the term ‘experimental philosophy’ in a book title. In 1663 he published Of the Usefulness of Experimental Philosophy which was soon followed by Henry Power’s Experimental Philosophy of 1664.

If we look at frequencies of use in Boyle’s writings, it turns out that he used the term ‘experimental philosophy’ roughly twice as often as ‘mechanical philosophy’ or ‘mechanical hypothesis’. This raw fact is in itself rather telling for those recent historiographical debates over the nature and status of mechanical philosophy in early modern philosophy that almost entirely ignore experimental philosophy. However, the key question is: Were the terms synonyms for Boyle or did they denote two different things?

The best early statement of Boyle’s view of the content of experimental philosophy is in the ‘Proemial Essay’ to Certain Physiological Essays first published in 1661. He starts with a criticism of previous natural philosophers such as Aristotle and Campanella:

they have too hastily, and either upon a few Observations, or at least without a competent number of Experiments, presum’d to establish Principles, and deliver Axioms. (Works of Robert Boyle, 1999–2000, 2: 13)

What experimental philosophers should do instead is:

set themselves diligently and industriously to make Experiments and collect Observations, without being over-forward to establish Principles and Axioms, believing it uneasie to erect such Theories as are capable to explicate all the Phaenomena of Nature, before they have been able to take notice of the tenth part of those Phaenomena that are to be explicated. (Works of Robert Boyle, 2: 14)

This clearly has to do with the role of observation and experiment in relation to theory in the acquisition of knowledge about nature. Now let’s see how Boyle defines the mechanical philosophy. In The Excellency and Grounds of the Mechanical Hypothesis (aka the mechanical or corpuscular philosophy) Boyle states the kernel of the view as follows:

the Universe being once fram’d by God, and the Laws of Motion being setled and all upheld by His incessant concourse and general Providence; the Phænomena of the World  thus constituted, are Physically produc’d by the Mechanical affections of the parts of Matter, and what they operate upon one another according to Mechanical Laws. (Boyle Works, 8: 104)

The mechanical affections referred to here are the shape, size, motion and texture of corporeal bodies.

Now this is really quite different from experimental philosophy. For, it is the sort of theory that one should arrive at as a result of practising experimental philosophy. This is why Boyle’s book The Origin of Forms and Qualities has a ‘speculative part’, which outlines the theoretical content of the mechanical philosophy, and a ‘historical (or experimental) part’, which provides experimental support for the speculative theory. Here is how he describes the relation between the two parts:

it was very much wish’d, that the Doctrines of the new Philosophy (as tis call’d) [i.e. mechanical philosophy] were back’d by particular Experiments; the want of which I have endeavour’d to supply, by annexing some, whose Nature and Novelty I am made believe will render them as well Acceptable as Instructive.

Thus, for Boyle, experimental philosophy and mechanical philosophy are entirely distinct: the former provides the evidential grounds of the latter. This is why, as Dmitri Levitin has shown, Boyle prefers Democritus to Epicurus. In Boyle’s view, the former based his atomism on experimental philosophy, the latter on speculative philosophy. (Levitin, ‘The experimentalist as humanist: Robert Boyle on the history of philosophy’, Annals of Science, 71, 2014, 149–82).

It may be that some philosophers and even natural philosophers conflated experimental philosophy with mechanical philosophy, but in Boyle’s mind they were distinct.


* Actually, the question turns out to be slightly more complicated than it looks because Henry More used the term ‘mechanical hypothesis’ in 1653 (An Antidote against Atheism, 44) and when Boyle first introduces the term in 1661 in Certain Physiological Essays, he uses ‘Mechanical Hypothesis or Philosophy’ (Boyle Works, 2: 87).