Kirsten Walsh writes…
In my last few posts, I’ve discussed some of the lesser-known aspects of Newton’s work. In my first post on this topic, I talked generally about how we might consider Newton’s chymistry, theology and Church history to be methodologically continuous with the experimental philosophy of the Principia and the Opticks. And in my second post I considered Newton’s alchemical tract, now referred to as ‘Of Natures obvious laws and processes in vegetation’, and identified several features that seem to highlight Newton’s early (albeit tacit) commitment to experimental philosophy.
In today’s post, I’ll begin to discuss an important but relatively understudied aspect of Newton’s work: his theological methodology. Since this blog is primarily concerned with early modern experimental philosophy, I’m going to start with the famous passage from the General Scholium to the Principia: “to treat of God from phenomena is certainly a part of natural philosophy”. The meaning of the first part of the statement is clear: we have epistemic access to God via our observations of the world. And so, from the phenomena, we can learn about God’s nature and divine will—in the same way that we can learn about, say, gravity. But in what sense is this ‘a part of natural philosophy’? That is, how does this statement fit with Newton’s stated views regarding that topic?
In the General Scholium, Newton explains that, while the laws of motion explain why celestial bodies move in Keplerian orbits, they cannot explain how celestial bodies come to be in their present orbits. And so, he writes, “This most elegant system of the sun, planets, and comets could not have arisen without the design and dominion of an intelligent and powerful being”. Prima facie, examples such as this don’t fit with Newton’s natural philosophical method. He seems to employ non-empirical background assumptions about the nature of God’s intervention to plug gaps in his theory. This looks dangerously close to feigning hypotheses. Moreover, from these assumptions, he seems to leap right to the first cause, blocking further scientific inquiry, and contradicting the ‘satis est’ attitude he adopts in his natural philosophy.
I think, however, that Newton’s treatment of God from phenomena is more consistent with his method of natural philosophy than it first appears. But to recognise this, we need to look more closely at how Newton approaches God from the phenomena. In fact, Newton treats of God from phenomena in several different ways. One approach is to move directly from the phenomena to the nature of God’s interactions with the world. For example, in the General Scholium, Newton notes that all celestial bodies move in regular orbits, which tells us that neither planets nor comets encounter any kind of resistance in their orbits. Newton uses the lack of resistance to argue that celestial bodies do not move through vortices but through empty space. However, this phenomenon also reveals that, while God is omnipresent and substantial, he is not material:
God is one and the same God always and everywhere. He is omnipresent not only virtually but also substantially; for action requires substance. In him all things are contained and move, but he does not act on them nor they on him. God experiences nothing from the motions of bodies; the bodies feel no resistance from God’s omnipresence (Principia, Cohen & Whitman translation, pp. 941-942).
Another way Newton approaches God is to ask after the nature of his interventions. Here, Newton identifies explanatory gaps between phenomena and theory, and asks whether God could be acting, and if so, what is the nature of that action? For example, in a letter to Bentley Newton notes that that his theory of universal gravitation can explain the motions of the planets, but not their original sizes or positions in the solar system. The latter, he concludes, can only be explained by divine intervention. That God works to achieve such perfect balance in the system of the world tells us that he is “not blind and fortuitous, but very well skilled in mechanics and geometry”. Here, the insight is that gravity can destabilise the system of the world—and so the physical world constantly tends towards decay. Thus, God is required to use his skills of design and maintenance to prevent this from happening.
Neither approach looks like ‘feigning hypotheses’. For one thing, Newton doesn’t allow his thinking about God to justify or constrain his theorising. Rather, God is introduced after the physical theory has been established to see what it can teach us about the nature of his intervention. And for another thing, Newton’s ideas about God don’t result from speculation, but from rigorous study of both scripture and the natural world, and the careful application of reason. It is from our post-Enlightenment perspective that rigorous study of scripture seems to fall outside of natural philosophy.
Moreover, Newton’s introduction of God doesn’t stop inquiry. Rather, it raises further questions about how and why God intervenes on the system of the world. And these, in turn, lead back to physical inquiry. For example, Newton’s discussions about God’s role in the sizing and positioning of the planets leads to a fruitful inquiry about the specific compositions of the planets and why the biggest planets are furthest from the Sun. That the inquiry continues highlights the fact that Newton doesn’t view the cause of a given phenomenon as either natural or supernatural: every phenomenon is generated by both natural and supernatural causes. That is, physical objects act on one another as natural causes, subject to physical and mathematical laws, but God is the first-cause, and hence, behind all actions. And so, when Newton treats of God from phenomena, the inquiry doesn’t end there.
Finally, as a good experimental philosopher, Newton knows that we only have direct epistemic access to the evidence of our senses, so our knowledge of God is necessarily limited. However, as he makes clear in query 28 of the Opticks, we mustn’t be put off by our inability to discover the first cause directly. Instead, we must work to uncover intermediate causes—proximate causes—and work slowly to uncover deeper and deeper levels of causes until we come to the first cause. And, importantly, these intermediate causes can also reveal the nature of God:
And these things being rightly dispatch’d, does it not appear from Phænomena that there is a Being incorporeal, living, intelligent, omnipresent, who in infinite Space, as it were in his Sensory, sees the things themselves intimately, and thoroughly perceives them, and comprehends them wholly by their immediate presence to himself… And though every true Step made in this Philosophy brings us not immediately to the Knowledge of the first Cause, yet it brings us nearer to it, and on that account is to be highly valued (Optics, Dover edition, p. 370).
Kirsten Walsh writes…
Over the weekend, I participated in a conference on ‘Newton and his Reception’, at Ghent University. I presented a paper based on my idea that Newton is working with an ‘epistemic triad’. I had an excellent audience in Ghent, and received some very helpful feedback, but I’d like to hear what you think…
To begin, what is Newton’s ‘epistemic triad’?
In his published work, Newton often makes statements about his purported method in order to justify his scientific claims. In these methodological statements, he contrasts things that have strong epistemic credentials with things that lack those credentials. Consider, for example, these passages from his early papers on optics:
- For what I shall tell concerning them is not an Hypothesis but most rigid consequence, not conjectured by barely inferring ’tis thus because not otherwise or because it satisfies all Phænomena … but evinced by ye mediation of experiments concluding directly & wthout any suspicion of doubt. (6 February 1672)
- I shall not mingle conjectures with certainties… (6 February 1672)
- To determine by experiments these & such like Queries wch involve the propounded Theory seems the most proper & direct way to a conclusion. (3 April 1673)
What these passages tell us is that Newton is making a distinction between theories, which are certain and experimentally confirmed, hypotheses, which are uncertain and speculative, and queries, which are not certain, but provide the proper means to establish the certainty of theories. I call this three-way division Newton’s ‘epistemic triad’, and argue that this triad provides the framework for Newton’s methodology.
To support this argument, I defended the following three theses:
Endurance thesis. There are some general features of Newton’s methodology that don’t change. These are characterised by the framework of the epistemic triad.
Developmental thesis. There are some particular features of Newton’s methodology that change over time. These can be characterised as a development of the epistemic triad.
Contextual thesis. There are some particular features of Newton’s methodology that vary with respect to context (namely, mechanics versus optics). These can be characterised as an adaptation of the epistemic triad to particular contexts.
The developmental and contextual theses are not news to most Newton scholars. It is commonly accepted that Newton’s methodology changed in important ways over the course of his life, and that there are methodological differences between Principia and Opticks. The endurance thesis is more problematic, so I made a special effort to show that Newton’s use of hypotheses is more consistent than we think. I argued that:
- In Principia, Newton appears to be working with the same implicit definition of ‘hypothesis’ that he works with in his early optical papers; and
- Hypotheses perform similar methodological roles in all of Newton’s natural philosophical work.
I need to do some more work to properly explicate this methodological role. But, to state it very broadly, Newton temporarily assumes hypotheses, which act as ‘helping premises’ in his inferences from phenomena. The fact that a statement may appear in Newton’s writing as a hypothesis, and then reappear later in a query, rule of reasoning, or phenomenon, has convinced many Newton scholars that Newton is inconsistent in his use of hypotheses. Against this conviction, I argue that Newton applies the label ‘hypothesis’ to things that perform a particular function, rather than to a particular claim.
Kirsten Walsh writes…
Last week I competed in the Otago University Three-Minute Thesis Competition. I had to explain my PhD thesis in no longer than three minutes. It was challenging indeed, in such a short length of time, to describe my research, communicate its significance and impart my enthusiasm for it – while pitching it at the level of an intelligent non-expert. Fortunately, I had great material to work with. There are so many interesting stories about Newton! Unfortunately, it’s often difficult to figure out which stories are true.
I opted to begin with the ‘approximately true’ story of Newton’s anni mirabilis, or miraculous years. The general thrust of the story is true, even if some of the particulars are false: the plague years mark a significant turning point in Newton’s scientific work. As Whiteside pointed out over forty years ago, we may
- “salute this first creative outburst – whether or not contained in one single marvelous year – of a man who twenty years afterwards was to construct a scientific Weltanschauung which is, in its essentials, still ours.”
So, with apologies to those of you with ‘historically sensitive’ ears, here is my script for the three-minute thesis competition:
It’s 1665. Cambridge has been struck by Plague, and Newton has been sent home from University. Summer is stretching out before him. Nice! What will he do on his extended summer holiday? Well, he did what I imagine most Scarifies* do on their summer holidays: he invented calculus, discovered the composition of light, and (after watching an apple fall from a tree) conceived the laws of universal gravitation… Okay, so perhaps Newton wasn’t quite your typical undergraduate student. The story about the apple is controversial, but everyone agrees about the discoveries. Scholars have called those years the ‘years of miracles’.
Why were they ‘miraculous’? Well, these were revolutionary discoveries – and there were so many of them. They provided the basic material for Newton’s Principia, and his Opticks. Enough material for a lifetime of publications! And real publications. Not just those ‘puff pieces’ that fill our journals nowadays. All in just 2 years!
Furthermore, these discoveries seemed to come out of nowhere. Newton was able to invent, discover and conceive things no one else could, because seemingly he had invented an entirely new scientific method. He had come up with a whole new way of mathematising physics, and claimed to have achieved mathematical certainty! Philosophers and scientists tried to emulate his method. But no one was as successful as Newton. Whatever Newton was doing, he was doing it right. But what was he doing?
This is the central question of my PhD, and it’s a question that dominates discussions of scientific method even now, 300 years later. But scholars still barely understand what Newton’s method was. Did Newton really think his scientific theories were as certain as mathematical proofs? Why did he think his theory of gravity was true, when he couldn’t even say for certain what gravity is? And, at the centre of it all, the question that’s been keeping me up at nights (as it has kept up generations of Newton-scholars before me): what did Newton mean when he wrote that enigmatic sentence at the end of Principia: ‘Hypotheses non fingo’; ‘I do not feign hypotheses’?
I do not feign hypotheses. What an odd thing to say. What does it even mean? ‘I haven’t invented these hypotheses’? ‘I didn’t prove them’? This sentence lies at the heart of my thesis. Unlike other Newton scholars, I think it describes a crucial aspect of Newton’s method. What it tells us is that Newton made a distinction. On the one hand, theories: mathematical, certain, experimentally confirmed. On the other hand, hypotheses: non-mathematical, uncertain, non-experimental, and speculative. This distinction is a crucial feature of Newton’s spectacularly successful scientific method. And I think it’s this distinction that explains Newton’s years of miracles.
The idea of anni mirabiles seems closely-related to the notion of a scientific revolution, which has been much discussed since Kuhn published The Structure of Scientific Revolutions in 1962. Philosophers of science disagree philosophically over the importance of revolutions to science, and historically over the occurrence of any genuine scientific revolutions. However, it is interesting to note that historians have recognised several anni mirabiles in the history of science. For example, 1543, the year that Vesalius published De Humani Corporis Fabrica and Copernicus published De Revolutionibus Orbium Coelestium. And 1905, the year that Einstein published his three ground-breaking papers in the Annalen der Physik. What role have these anni mirabiles played in the history of science? What do they tell us about scientific progress? Norwood R Hanson once said:
- “It is possible both to be driven by intuition and at the same time to reason carefully. Most scientific discoveries, indeed, result from just such an intertwining of headwork and guesswork.”
What do you think?
*Otago Undergraduate Students
Kirsten Walsh writes…
Newton’s famous pronouncement, Hypotheses non fingo, first appeared in 1713, but Newton’s anti-hypothetical stance is present as early as 1672, in his first papers on optics. In his first publication, he introduces his notion of certainty, and insists that his doctine of colours is a theory; not an hypothesis:
- For what I shall tell concerning [colours] is not an Hypothesis but most rigid consequence… evinced by ye mediation of experiments concluding directly & without any suspicion of doubt.
Despite these clear anti-hypothetical themes, a corpuscular hypothesis lies beneath Newton’s theory of light and colours. What are we to make of this? Is Newton guilty of feigning an hypothesis? Is Wolff correct when he says that Newton “indulges in hypotheses in those very areas in which they think he abstained from employing them“?
To begin, what does Newton mean by Hypotheses non fingo? ‘Fingo’ has been variously translated as ‘frame’, ‘make’, ‘imagine’ and ‘devise’. Experts argue that ‘feign’ is the most appropriate translation. While it has a variety of meanings, such as to form, to invent, to forge, or to suppose erroneously, the word ‘feign’ also carries the nuance of pretence, counterfeit, or sham. Thus, they argue that while Newton indeed conceived or framed hypotheses, he did not attach any special epistemic status to them. He maintained a clear demarcation between theories that were supported by experimental results and hypotheses that were merely unsupported speculations.
Now let’s take a closer look at Newton’s early optical papers. Newton claims that his doctrine of colours is a theory, not an hypothesis, for three reasons:
- It is certainly true, because it is supported by (or deduced from) experiment;
- It concerns the physical properties of light, rather than the nature of light; and
- It has testable consequences.
These are the three key aspects of Newton’s early methodology. He refers to them again and again throughout the debate that followed the publication of his first optical paper.
Newton explicates his corpuscularian view in his first optical paper and describes light rays as substantial bodies. But when his opponents accuse him of hypothesising, Newton argues that he is not guilty. Firstly he argues that this hypothesis is not necessary for his explanation of colours. Secondly he argues that he attaches no special epistemic merit to his hypothesis because:
- It is not supported by experiment;
- It concerns the nature of light; and
- It has no testable consequences.
While Newton never gives up his corpuscularian view, he attempts to explicate and promote his theory without referring to it. He argues that he doesn’t need to provide any hypothesis on the nature of light – his theory on the properties of light is sufficient on its own.
I claim that Newton isn’t guilty of violating his anti-hypothetical stance. He demonstrates that he can distinguish between theory and hypothesis, giving the former higher epistemic status than the latter. He does not pretend to have empirical support for his corpuscular hypothesis, nor does he try to ‘prop it up’ on other grounds. Perhaps he regrets having ever opened the proverbial can of worms, for the next time he explicates his theory of light and colours, he does so without any reference to the corpuscular hypothesis or the nature of light.
That Newton can tell the difference between good scientific explanations and speculations is further supported by his use of queries in these early optical papers, but more on this next time. To conclude, I think Newton is not guilty of feigning an hypothesis. What do you think?