Why was the mechanical philosophy so widely adopted in the seventeenth century?

The mechanical philosophy is perhaps the core element of the Scientific Revolution. Its adoption was dependent on the ideas encompassed by it to be accepted. In this essay I will describe the main facets of the mechanical philosophy and then discuss why it was taken up to the extent it was in the seventeenth century.

In essence the mechanical philosophy states that “all phenomena were to be explained in terms of concepts employed in the mathematical discipline of mechanics: shape, size, quantity and motion”. (John Henry, ‘The Scientific Revolution and the Origins of Modern Science’, p69.) It seeks to look at the world in terms that can be closely compared with machinery – the actions of one body, or a part of that body, acting on or affecting another. The mechanical philosophy also holds that everything in nature is made up of microscopic particles called atoms. This links in with the theories of Democritus, and more importantly of Epicurus. This was not agreed on by all the mechanists, some of whom whilst not agreeing on the existence of infinitely divisible particles, investigated the possibility of fundamentally small particles involved in physical change.

In order to understand why the mechanical philosophy had the impact it did it is necessary to establish the background environment which was present prior to the Renaissance. Scholastic natural philosophy with Aristotelianism at its centre, and combined with the medical ideas of Galen, and the model of the universe provided by Ptolemy, had pretty much dominated European thought since the thirteenth century. The central concern of Aristotelianism was with qualities, or a qualitative understanding of the world. For example, “all heavenly motions were natural, unforced motions, and that the natural tendency of heavenly bodies was to move uniformly, in perfect circles.” (Henry, p16). In fact Aristotle thought that the world was eternal and had always existed the way it was now.

So out of this seemingly stable view of the world what changed? John Henry suggests we look for the causes of the Scientific Revolution among the wider changes happening throughout Europe during the sixteenth and seventeenth centuries. The mechanical philosophy is a central theme of the Scientific Revolution and one important way we can understand its impact is to sum up what took place in that revolution. Natural philosophy in the Middle Ages followed the Aristotelian concern with qualities, not quantities, so mathematics did not come under the umbrella of concern for a natural philosopher.

However, with the Scientific Revolution came a change that saw a mathematical approach to looking at the natural world come more to the fore. During the Middle Ages theories derived mathematically were put forward on a hypothetical basis. However a more Realist – “the belief that the sciences reveal to us the way things really are”, (Henry, p149) – view which put forward the idea that analysing a phenomenon mathematically shows how things must be true because it is the nature of mathematics to do so. This would give authenticity to any idea put forward on this basis, and thereby help it to become accepted and adopted. The mathematisation of nature had the effect of increasing the stature of mathematicians from practitioners to one where mathematics was a necessary tool for natural philosophers to possess, and because mathematics was becoming an accepted tool for demonstrating aspects of nature it would follow that the ideas of the natural philosophers would be more readily accepted. One such man was Galileo Galilei (1564 – 1642), who while working within the university system had to be satisfied with being a lowly paid mathematicus who had to defer to the natural philosophers and their higher status. But partly out of his endeavors to improve on the Aristotelian account of motion, he was able to negotiate the higher, more prestigious post of natural philosopher at the court of Cosimo de’ Medici. This gave a boost to his stature in society and gave his ideas a greater chance of being adopted.

Galileo is best known for his work on the ideas of Copernicus, but just as importantly to the adoption of the mechanical philosophy he took Aristotle’s ideas on motion and was able to prove, using mathematics that disregarding wind resistance acceleration in free fall is a constant for all objects regardless of their weight. He also worked out that the parabolic path of a projectile combined two motions acting simultaneously – the unnatural motion that the object was subjected to plus the natural motion of its free fall. Galileo’s work on terrestrial mechanics in some ways sets the scene for Isaac Newton’s (1642 – 1727) work on the laws of motion, which was the high point of the English tradition of the mechanical philosophy.

Isaac Newton by publishing his Principia Mathematica in 1687 was able to put forward his new natural philosophy and set out his laws of motion, based on mathematical principles because the mathematics was substantially correct. He did not have to justify this approach because the validity and intellectual status of mathematics as a fundamental part of the mechanical philosophy was already established. The mathematisation of natural philosophy can thus be seen to have played a role in ensuring the acceptance and adoption of the mechanical philosophy.

The adoption of the mechanical philosophy was also influenced by its role in medical advances. Descartes worked on aspects of physiology and looked at the possibility that the workings of animal and human bodies were closely related to hydraulic systems. “He included his account of the movement of the heart and blood in his discourse on Method (1637) as an indication of how a mechanistic physiology would work. It proved to be extremely influential and mechanistic attempts to explain life gathered momentum throughout the century” (Henry, p80). On the whole though medicine was slower than other areas to fully adopt the ideas of the mechanical philosophy. The humoural system of Galen proved to be very stubborn and it continued to be influential for much of the eighteenth century, albeit with a few enhancements from the mechanical philosophy – in particular the corpuscular theory of Robert Boyle.

What other factors were present in the Renaissance that could be said to have influenced the eventual acceptance of the mechanical philosophy? Most significantly perhaps in seventeenth century England social status was very important. Men such as Newton and Boyle – two people central to the mechanical philosophy – were gentlemen. Their audience were much more likely to adopt what they were saying because as gentlemen they must be telling the truth. In the seventeenth century it was taken as fact that gentlemen ought to be arbiters of truth, i.e. that their ideas and utterances could be relied on to be trustworthy. “Why was the gentleman said to be a truth-teller? What features of his nature, his situation, and his aspirations were said to underwrite the reliability of his truth-telling”? (Steven Shapin, ‘A Social History of Truth’, p74-75).

Most importantly the truthfulness of a gentlemen arises from the circumstances of his social economic and political position. Dr. Johnson stated that “Truth is scarcely to be heard but by those from whom it can serve no interest to conceal it” (Samuel Johnson, ‘The Rambler’ vol. V, 37). The main proponents of the mechanical philosophy were gentlemen – Robert Boyle for example was the son of Richard Boyle, first earl of Cork. They had nothing to prove; their rank in society and their economic independence meant they had no conflict of interest that would prevent them from putting forward trustworthy ideas. A gentlemen “ought to behave thus or it would be reliably concluded that one was not the type of person one claimed to be. Lying was vile, base, mean and ignoble because it arose from circumstances attending the lives of ignoble people” (Shapin, p83). Boyle and Newton were gentlemen in this sense, so it could be relied upon that the ideas they put forward on the mechanical philosophy were true.

The seventeenth century audience of the mechanical philosophy not only was receiving knowledge of new ideas or ‘things’ but also was receiving knowledge of the people putting them forward. So-called ‘thing’ knowledge and ‘people’ knowledge are inextricably linked. “In securing knowledge we rely upon others and we cannot dispense with that reliance. That means that the relations in which we have and hold our knowledge have a moral character, and the word I use to indicate that moral relation is trust” (Shapin, pXXV). So Isaac Newton’s audience relied upon him to deliver his principia and that the relationship they had with the knowledge it contained enabled them to trust it. Further, “What we recognize as people – knowledge is a necessary, not a sufficient condition for the making of thing – knowledge” (Shapin, pXXVI). So what the seventeenth century audience of the Principia knew about mathematical natural philosophy contained what they knew of Newton; and what they knew about the moral character of Newton was informed by his Principia. It is these two things working together which ensured that it was accepted and adopted.

The mechanical philosophy became widely adopted in the seventeenth century through a combination of influences. Primarily it was a philosophy that developed and used mathematical disciplines and as such had the seeds of its adoption built in, because mathematics was a discipline that self-evidently gave a ‘Realist’ picture. The mechanical philosophy was also able to rely on the social influences of the times to become accepted because the status of the mechanists themselves ensured the favorable attention of their ideas.