How influential was Newtonian natural philosophy?
Newton had a huge influence on the progression of natural philosophy but his approach was different to that of Aristotle; particularly in its strong emphasis on the importance of the experiment and his explicit rejection of hypotheses. He was an architect of the mathematisation of nature and this write up attempts to show how this affected post-Newtonian natural philosophy. In addition, Newton's obsession with alchemy played a substantial part in formulating his style which was a lot more ambiguous than it sometimes seems. Although in the twentieth century he is frequently dubbed "the great British physicist", there are several other interpretations of the man and his work.
Experimental natural philosophy
In Newton's seminal work, Philosophiæ Naturalis Principia Mathematica, he made the famous statement: "hypotheses non fingo." This is commonly translated from the Latin as "I frame no hypothesis" and does a significant amount to summarise the novel aspects of his brand of natural philosophy. Newton disliked conjectural explanations because they lacked a cogent argument and were solely supported because observations could be directly deduced from them. Rather, his brand of natural philosophy relied on "forces" that were unequivocally demonstrated by his experience and experiments instead of one of a multitude of airy hypotheses. Newton's preference for empiricism was exemplified by his various proofs "by experiment." He claimed that the precise detail with which he recorded his methods was instrumental to the perceived validity of his theories and said that the only genuine attempts to rebut them was by experiments of equal precision but with contradictory outcomes. His emphasis on empirical method bore great influence and, by the time Opticks was published, Newton's critics used predominantly experimental arguments. Indeed, the new treatises on optics of the early nineteenth century all used exact descriptions of carefully conducted experiments.
Newton's style of natural philosophy bears a stark contrast to that based on Aristotelian causation where bodies are only influenced by pushes and pulls - a billiard ball could be said to move off in a particular direction because it had been struck by the cue ball. Where there is no obvious cause for an observed interaction (such as the attraction of magnets or a salt dissolving in a solvent) an "occult" power was said to be at work. However, this did not stand up to scrutiny or detailed analysis - Newton sought to explain physical events and changes empirically and aimed for a "reduction of all phenomena to the operation of a small number of active principles of motion."i Newton's natural philosophy had the strength that it managed to supply easy-to-understand explanations in terms of forces. The imagery associated with the traditional tale about an apple striking his head is especially important as it began to reduce credence in the Aristotelian idea of the untouchable harmony of heaven. Instead, Newton's apple associates the familiar actions on earth with those of the universe – the same forces apply as the apple falls to the ground as when the moon "falls" around the earth. "Toward the start of the nineteenth century, a new style of scientific research was established that advocated a deliberate and explicit integration of natural philosophical theories with mathematics and experiments,"ii and so the mechanisation of natural philosophy began.
Not only did Newton contribute to natural philosophy, but he promoted a particular view of it which was opposed to the old peripatetic principles. While, admittedly, there was not the vastest difference, Newton extended the Aristotelian ideas and accepted explanatory principles that were yet to be explainable. This allowed for "unprecedented possibilities of application … which would have remained closed forever to the orthodox mechanicists of the seventeenth century."iii His style of natural philosophy was distinct not only because it favoured experiments over hypotheses but also as Newton notably did much to encourage the overlap of mathematics and natural philsophy. The mathematisation occurring at the time helped provide the geometry that assisted him in developing his reflecting telescope and, more famously, the theory that white light is composed of a spectrum of colours. At first this mechanical style of natural philosophy drew antipathy or was only partially acknowledged but, over time, the most renowned scientists began to accept it.
Newton the alchemist
After Keynes' lecture to the Royal Society in 1942, Newton's penchant for alchemy and magic has been widely known. His notebooks and journals were deemed "of no scientific value" and Keynes himself scoffed at the idea that such a respected scientist should have been so preoccupied with sorcery. However, Newton's dabblings may have been essential to formulating his experimental method and he may have even discovered the force of gravity through magical induction rather than the Aristotelian brand of natural philosophy. Magicians did not construct hypotheses or even attempt to explain causes or reasons behind phenomena. The central concern of magic is learning what causes what by experiment and there is no scope to learn why. It is fair to question how great a role Newton's alchemical work had in formulating his style of natural philosophy.
However, it cannot be denied that Newton received his share of criticism. Throughout his working life he was continually corrected and vehemently rebutted and not all the attacks were against the values he put forward rather than his theories of natural philosophy. His methods were not fully accepted and Huygens among others lodged objections to the way he worked. Despite his assertion, "hypotheses non fingo," later in his career Newton was increasingly willing to draw fanciful conjectures. He laid out an extensive body of fact drawn from careful observations in Opticks, and afterward included propositions unsupported by experimental verification. With ambiguous phrasing he did not go as far as making flat hypotheses, but he did allow "philosophical" conjectures that were general in nature and not backed up by mathematics. Newton was a deeply religious man who professed to read the Bible every day and tried to make his conclusions conductive to Christianity as he worried that natural science was beginning to allow atheism to gain ground. However, contrary to his intentions, the escalating divisions and separation of religion and science in the years following his death relied substantially on the foundations of his work. The development of natural philosophy (and later, science) was probably not in the spirit he would have wanted. Newton rejected the wave theory of light and his methods imposed certain restrictions on scientific practise in the future. Lastly, he exerted his influence in England to great effect but this had the result that Leibniz' superior brand of calculus was largely disregarded. This meant that English mathematicians were, in some ways, lagging behind their European counterparts.
Newton's lasting effect on the progression of science cannot be denied. Although it took time for his reputation to reach the height of today, he was greatly revered at death and there were numerous dedications to his memory. We still owe him many great discoveries such as that of gravity, and his three laws of motion are taught to pupils in every school. In comparison to peripatetic methods, Newton was responsible for a considerable change in the way natural philosophy was practised and thought about while few deny that he massively increased human understanding of the universe. Newton today is regarded as a genius and probably the most influential British scientist in history, but his influence was not all positive nor immediately noticeable. As science became more important in the nineteenth century, so did his import and recognition. While during his lifetime he was a renowned natural philosopher, it was only later that his full legacy became apparent.
- i Dijksterhuis, E. J. The Mechanisation of the World Picture, 327, p. 489 (Oxford, 1961).
- iiFauvel, John. Let Newton Be!, IV, p. 98 (Oxford, 1988).
- iii Dijksterhuis, E. J. The Mechanisation of the World Picture, 327, p. 490 (Oxford, 1961).
- Fara, Patricia. Pandora's Breeches: Women, Science and Power in the Enlightenment (2004).