Kirsten Walsh writes…
In my last post, I started thinking about the lesser-known aspects of Newton’s work—his chymistry, theology and Church history—in order to learn more about his methodology. In particular, I wondered what kinds of methodological continuity, if any, there are across his many projects. In this post, I’ll focus on a tract, now referred to as ‘Of Natures obvious laws and processes in vegetation’, from Newton’s alchemical corpus. Newton probably wrote this piece in 1672—the year that he wrote his ‘New Theory of Light and Colour’. The piece represents Newton’s attempt to give a synopsis of his early alchemical reading and to come up with, essentially, a ‘theory of everything’.
There is a great deal to interest us in this tract, including an early mechanical-æthereal theory of gravity and a discussion of the nature of God. But here, I’ll focus on one idea: Newton’s distinction between mechanical processes and vegetative processes. Where ‘vegetation’ is the generative process through which animals, plants and minerals grow, putrefy and regenerate themselves, ‘mechanical’ processes involve adding, subtracting and rearranging parts (described as “a gross mechanical transposition of parts” (5r)). Newton considers these processes to be exhaustive: “Natures actions are either vegetable or purely mechanical” (5r).
Newton’s discussion of this idea highlights several methodological continuities. I’ll discuss two of them here.
The first concerns the way Newton infers physical processes from observed phenomenal patterns. Drawing comparisons across the ‘three kingdoms of nature’—animal, vegetable and mineral—Newton notes that some metals grow, putrefy and regenerate within the Earth, much in the way that trees grow out of the earth, suggesting that some metals and minerals ‘vegetate’. In contrast, some salts and minerals appear to generate by the simple combining and arranging of parts. And so Newton proposes that there are two distinct processes at work in nature: vegetative and mechanical. The postulated distinction in turn guides further exploration of natural phenomena, enabling him to unify some patterns of generation and to differentiate others. The phenomena he explores go well beyond the initial cluster of metals and salts, eventually including organic life, heat and flame, and gravitation. And these phenomena, in turn, offer further clues about nature’s hidden processes. In short, observed phenomena illuminate underlying processes, which, in turn, guide further exploration of phenomena.
We see Newton engaging in similar inferential patterns in both the Principia and the Opticks. In the Principia, from the observed Keplerian orbits of the planets, Newton infers the inverse-square centripetal force. The inverse-square force, in turn, guides Newton’s exploration of other celestial phenomena, allowing him to calculate the motions of comets, the shapes of planets, and also to correct for perturbations of orbits. Similarly, in the Opticks, from the phenomena of the unequal refraction of light, Newton infers the heterogeneity of white light. The heterogeneity of white light, in turn, guides Newton’s exploration and theorising of other optical phenomena, including the colours of thin plates, thick plates and coloured fringes. In other words, this inferential feedback loop between phenomena and processes appears to be a standard feature of Newton’s methodology. In Query 31 of his Opticks, Newton describes this in terms of the joint methods of ‘analysis’ and ‘composition’. ‘Of Natures obvious laws’ might be considered an early manifestation of this method.
A second feature worth considering is the way Newton operationalised the concept of vegetation in order to develop a quantitative test for such processes. The term ‘vegetative’ was familiar to those concerned with the study of life and vitalism, and Newton was happy to speculate on the nature of this process:
The principles of her vegetable actions are noe other than the seeds or seminal vessels of things those are her onely agents, her fire, her soule, her life (5r).
But such a qualitative description of the process wasn’t very helpful for establishing which phenomena were generated by which processes. Especially since, as he noted, some natural phenomenon might appear to have been generated through vegetative processes, but in fact be produced mechanically. The way to distinguish between the two kinds of effects was to analyse them—i.e. break the entity down into its parts—and then try to put it back together again. If the recomposition was successful, then this indicated mechanical processes, if it wasn’t, then vegetative processes were operative. And so the methods of resolution and composition, or analysis and synthesis, provided him with a way of testing for vegetative processes. And thus ‘vegetation’ was effectively operationalised: the concept was defined through the operations which tested for it.
We see Newton engaging in a similar practice in his study of interference phenomena. His hypothesis on the nature of light postulated a hypothetical cause for the observed pattern of coloured rings: an æthereal ‘pulse’. Operationalising the concept of a pulse gave Newton a unit of measurement and, eventually, a way of formalising and abstracting the explanation. I have argued that Newton’s hypotheses played sophisticated supporting roles in his optical investigations. The role performed by the hypothesis of vegetation in this alchemical tract, and the way Newton links it to observation and experiment, looks similarly rich and sophisticated.
This feature helps me to say something more specific about, what I have termed, Newton’s ‘rhetorical style’. As I have noticed in previous posts, Newton took familiar terms and stretched them to fit his methodology. It is well-known that he did this with physical concepts such as ‘force’ and ‘mass’, and I have shown, on this blog, that he did this with methodological concepts such as ‘query’, ‘hypothesis’ and ‘principle’. Bill Newman has demonstrated that Newton also borrowed the concepts of ‘analysis’, ‘synthesis’ and ‘redintegration’ from chymistry and adapted them to his optical work—massaging them to fit his own needs. But Newton’s use of ‘vegetation’ highlights a particular feature of his rhetorical style: Newton took common terms with imprecise, qualitative meanings and defined them in terms of methods which measure, quantify or detect certain processes. And so what was really innovative in this case wasn’t that Newton used analysis and synthesis to investigate salts and metals, but rather, that he defined mechanical and vegetative processes in terms of that kind of intervention. In other words, Newton’s rhetorical style involved operationalising concepts—turning them into tools of measurement.
I closed my last post by pointing out that Newton’s efforts to pass off his published work as experimental philosophy may well have been politically motivated: by describing his work as ‘experimental philosophy’, he was signalling his commitment as much to the Royal Society as to observation- and experiment-based theorising. Newton’s chymical papers were circulated much more privately and so, presumably, the same political motivations didn’t apply. Moreover, Newton did not describe himself as an ‘experimental philosopher’ in his published work until 1713. So it is not surprising that we find no explicit mention of experimental philosophy or the methods of the Royal Society in this tract, which predates that explicit declaration by at least 40 years. However, the two features I’ve identified highlight Newton’s commitment to observation- and experiment-based theorising. That this commitment is evident, absent of any political pressure, suggests that it was genuine.