Kirsten Walsh writes…
In my last two posts, I have discussed my alterations to the 20 theses of our project. In this post, I’ll continue to discuss thesis 8.
In 2011, I claimed that:
- 8. The development of Newton’s method from 1672 to 1687 appears to display a shift in emphasis from experiment to mathematics.
But at the start of this year, I replaced this thesis with a new thesis 8:
- 8. In his early work, Newton’s use of the terms ‘hypothesis’ and ‘query’ are Baconian. However, as Newton’s distinctive methodology develops, these terms take on different meanings.
In my last post, I told you that I decided to remove my original thesis 8 because the methodological differences between Newton’s early papers and Principia aren’t as great as I initially thought. This isn’t to say that I now think that the methodology of the 1672 paper is precisely the same as the methodology displayed in Principia. Rather, I don’t think my original thesis 8 captures what is important about these differences.
In today’s post, I’ll tell you about my new thesis 8.
On this blog, we have argued that the early members of the Royal Society adopted the new experimental philosophy in a Baconian form. Newton initially encountered the experimental philosophy in the early- to mid-1660s through his reading of Boyle, Hooke and the Philosophical Transactions. While he never adopted the Baconian method of natural history, other features of his early methodology resemble the Baconian approach. For example, in Newton’s 1672 paper and the debate that followed, his use of experiment and queries, and his anti-hypothetical stance, were recognised and accepted by the Baconian experimental philosophers. Moreover, his 1675 paper, in which he explored his hypothesis of the nature of light, was recognised by his contemporaries as an acceptable use of a hypothesis.
In Newton’s later work, however, hypotheses and queries look quite different.
Firstly, consider Newton’s Opticks. When the Opticks was published in 1704, it contained no hypotheses, and the introduction explicitly stated that:
- “My Design in this Book is not to explain the Properties of Light by Hypotheses, but to propose and prove them by Reason and Experiments.”
Book III ended with a series of queries, which provided directions for further research, in the style of Baconian queries. E.g.:
- “Query 2. Do not the Rays which differ in Refrangibility differ also in Flexibility…?”
However, in the 1706 and 1718 editions, Newton introduced new queries, which explore the nature of light. E.g.:
- “Qu. 29. Are not the Rays of Light very small Bodies emitted from shining Substances?”
Like the earlier queries, these ones set out a new research program. But they are much more speculative than was acceptable according to the Baconian method.
Now consider Newton’s Principia. There are hypotheses in every edition of Principia, but they look nothing like Newton’s 1675 hypothesis. In particular, they do not explore the nature of things. For example:
- “Hypothesis 1. The centre of the system of the world is at rest.”
I have argued that the hypotheses in Principia provide a specific supportive role to theories. These propositions are temporarily assumed in order to draw out the observational consequences of Newton’s theory of gravitation. They are simplifying assumptions; not assumptions about the nature of gravity.
Previously, I have argued that Newton’s methodology should be seen as a three-way epistemic distinction between theories, hypotheses and queries. I call this an ‘epistemic triad’. I claim that Newton took these, already familiar, terms and massaged them to fit his own three-way epistemic distinction. It is important to recognise, therefore, that the triad is a three-way epistemic division, rather than the juxtaposition of three terms of reference. The terms ‘theory’, ‘hypothesis’ and ‘query’ are simply labels for these epistemic categories.
In fact, this is a feature of many of Newton’s innovative concepts. He borrowed familiar terms and massaged them to fit his own needs. I have shown that he did this with his key methodological terms: ‘theory’, ‘hypothesis’ and ‘query’. Steffen Ducheyne has argued that Newton did this in other aspects of his methodology, such as his dual-methods of analysis and synthesis. This suggests that Newton’s labeling and naming of things was very much post hoc. It seems that, when discussing Newton’s methodology, we should emphasize divisions and functions over definitions.