{"id":1636,"date":"2011-11-07T12:00:05","date_gmt":"2011-11-07T00:00:05","guid":{"rendered":"https:\/\/blogs.otago.ac.nz\/emxphi\/?p=1636"},"modified":"2011-11-08T19:03:09","modified_gmt":"2011-11-08T07:03:09","slug":"the-aims-of-newton%e2%80%99s-natural-philosophy","status":"publish","type":"post","link":"https:\/\/blogs.otago.ac.nz\/emxphi\/the-aims-of-newton%e2%80%99s-natural-philosophy\/","title":{"rendered":"The Aims of Newton\u2019s Natural Philosophy"},"content":{"rendered":"

Kirsten Walsh writes…<\/strong><\/p>\n

In a previous post<\/a> I discussed the aim of absolute certainty in Newton\u2019s early optical papers.\u00a0 I argued that this aim provides the link between Newton\u2019s mathematical and experimental methods.\u00a0 This quest for certainty is an enduring feature of Newton\u2019s natural philosophy, leading to a modest natural philosophical agenda.\u00a0 For example, in the General Scholium<\/a> to the Principia<\/em> (1713), Newton writes:<\/p>\n

    \u201cI have not as yet been able to discover the reason for these properties of gravity from phenomena, and I do not feign hypotheses … And it is enough that gravity really exists and acts according to the laws that we have set forth and is sufficient to explain all the motions of the heavenly bodies and of our sea.\u201d<\/ol>\n

    But is this really<\/em> enough, for Newton?\u00a0 Apparently it\u2019s not.\u00a0 In the very next paragraph, Newton begins to speculate on the \u201csubtle spirit\u201d that permeates bodies and might be operative in various phenomena.\u00a0 It looks like he is proposing a causal explanation of universal gravitation.\u00a0 However, these speculations end before they really begin, when Newton concludes that \u201cthere is not a sufficient number of experiments to determine and demonstrate accurately the laws governing the actions of this spirit.\u201d<\/p>\n

    This is the final line of Principia<\/em>.\u00a0 And, for such a controversial book, this is a rather inauspicious ending.\u00a0 But I think we can glean something about the aims of Newton\u2019s natural philosophy from this.<\/p>\n

    To begin, we need to distinguish between what Newton wants<\/em> to achieve, and what he thinks he can<\/em> achieve.\u00a0 Newton wants to give a complete, true theory of the world \u2013 including an account of the motions of the planets, the cause of gravity, and even God\u2019s relation to the natural world.\u00a0 But, in the trade-off between completeness and truth, Newton sides with truth.\u00a0 For, as he writes in an unpublished Preface to Principia<\/em> (mid-1710s), \u201cstill it is better to add something to our knowledge day by day than to fill up men\u2019s minds in advance with the preconceptions of hypotheses.\u201d<\/p>\n

    Newton\u2019s modesty and restraint should not be misinterpreted as lack of epistemic ambition.\u00a0 The surest way to achieve absolute certainty would be to keep his domain of inquiry as narrow as possible.\u00a0 But Newton doesn\u2019t do this.\u00a0 Instead, he pushes at the boundaries of what can be known with certainty.\u00a0 This is demonstrated by his use of Baconian Induction<\/a> to make increasingly general claims about gravity.\u00a0 Newton ambitiously generalises from pendulums, to terrestrial bodies, to all bodies. \u00a0In an unpublished Preface to Principia<\/em>, he writes:<\/p>\n

      \u201cBut it has also been shown in the Principia<\/em> that the precession of the equinoxes and the ebb and flow of the sea and the unequal motions of the moon and the orbits of comets and the perturbation of the orbit of Saturn by its gravity toward Jupiter follow from the same principles and what follows from these principles plainly agrees with the phenomena.\u201d<\/ol>\n

      So what do those final two paragraphs of the General Scholium tell us about the aims of Newton’s natural philosophy?\u00a0 I. Bernard Cohen<\/a> says that the General Scholium is similar to the discussions that are found in scientific papers today: Newton is discussing the implications of his results and suggesting areas of further research.\u00a0 On this reading, Newton is saying that there are two jobs ahead:<\/p>\n

        \n
      1. To give a causal explanation of gravity; and<\/li>\n
      2. To apply the theory of gravity to other phenomena in order to solve other problems.<\/li>\n<\/ol>\n

        Importantly, Newton thinks that we can begin on (2) without waiting to complete (1).\u00a0 This is why Newton says it is enough that he has established that gravity exists and acts according to certain laws.<\/p>\n

        Related Posts: Newton on Certainty<\/a>, Newton’s 4th Rule for Natural Philosophy<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

        Kirsten Walsh writes… In a previous post I discussed the aim of absolute certainty in Newton\u2019s early optical papers.\u00a0 I argued that this aim provides the link between Newton\u2019s mathematical and experimental methods.\u00a0 This quest for certainty is an enduring […]<\/p>\n","protected":false},"author":4582,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[113],"tags":[274,224],"class_list":["post-1636","post","type-post","status-publish","format-standard","hentry","category-ideas","tag-certainty","tag-newton"],"_links":{"self":[{"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/posts\/1636","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/users\/4582"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/comments?post=1636"}],"version-history":[{"count":0,"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/posts\/1636\/revisions"}],"wp:attachment":[{"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/media?parent=1636"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/categories?post=1636"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/tags?post=1636"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}