{"id":2999,"date":"2012-12-17T16:00:14","date_gmt":"2012-12-17T04:00:14","guid":{"rendered":"https:\/\/blogs.otago.ac.nz\/emxphi\/?p=2999"},"modified":"2012-12-16T17:39:51","modified_gmt":"2012-12-16T05:39:51","slug":"did-newton-adopt-hypothetico-deductivism","status":"publish","type":"post","link":"https:\/\/blogs.otago.ac.nz\/emxphi\/did-newton-adopt-hypothetico-deductivism\/","title":{"rendered":"Did Newton Adopt Hypothetico-Deductivism?"},"content":{"rendered":"

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

In 1718, Newton published the second edition of Opticks<\/em><\/a>.\u00a0 Query 23 was renamed Query 31, and in this query Newton expanded on his method of analysis.\u00a0 He wrote:<\/p>\n

    \u201cIf no Exception occur from Ph\u00e6nomena, the Conclusion may be pronounced generally.\u00a0 But if at any time afterwards any Exception shall occur from Experiments, it may then begin to be pronounced with such Exceptions as occur.\u201d<\/ol>\n

    At first glance, this passage suggests that Newton adopted the hypothetico-deductive method<\/a>, in that the epistemic status of a theory is sensitive to new evidence.\u00a0 However, if we consider how Newton put this methodology into practice, in Principia<\/em> <\/a>book III, we will get a different reading of this passage.<\/p>\n

    In the 3rd<\/sup> edition of Principia<\/em>, Newton introduced a 4th<\/sup> rule of philosophising<\/a>:<\/p>\n

      “In experimental philosophy, propositions gathered from phenomena by induction should be considered either exactly or very nearly true notwithstanding any contrary hypotheses, until yet other phenomena make such propositions either more exact or liable to exceptions.”<\/ol>\n

      The similarities between this rule and the earlier passage from Query 31 are striking: that new evidence can make a proposition \u201ceither more exact or liable to exceptions\u201d is similar to pronouncing the conclusion either \u201cmore generally\u201d or \u201cwith such Exceptions as occur\u201d.\u00a0 So looking at how this rule was employed should tell us a lot about how to interpret the earlier passage.<\/p>\n

      In Principia, <\/em>Newton only explicitly employed rule 4 once: in proposition 5 book III.\u00a0 In this proposition, Newton made his argument for universal gravitation by generalising step-by-step from the motions of the planets around the sun, and the satellites of Saturn and Jupiter around their respective centres, to the forces producing those motions. \u00a0Newton introduced three corollaries, the third of which states that \u201call planets gravitate towards one another\u201d.<\/p>\n

      In the scholium following this corollary, Newton said:<\/p>\n

        \u201cHitherto we have called \u2018centripetal\u2019 that force by which celestial bodies are kept in their orbits.\u00a0 It is now established that this force is gravity, and therefore we shall call it gravity from now on.\u00a0 For the cause of the centripetal force by which the moon is kept in its orbit ought to be extended to all the planets, by rules 1, 2, and 4.\u201d<\/ol>\n

        Rules 1 and 2 tell us not to postulate more causes than necessary, and that we should assume that effects of the same kind have causes of the same kind.\u00a0 In this context, rule 4 tells us that, if exceptions to universal gravitation occur, then instead of reducing our credence in the theory, we should reduce the scope <\/em>of the theory: it is still true, but true of less instances.\u00a0 De-generalising a theory doesn\u2019t reduce its certainty; rather, it reduces the scope of the theory while maintaining its certainty.\u00a0 So according to rule 4:<\/p>\n

          \n
        1. In the absence of exceptions, we should take gravity to be universal.<\/li>\n
        2. If exceptions to universal gravitation are found, we should infer that the domain of gravity is limited (i.e. not universal).<\/li>\n
        3. We should not allow our assumptions about matter theory (e.g. the improbability of action at a distance) to have any influence on our epistemic attitude towards universal gravitation.<\/li>\n<\/ol>\n

          Instead of reading rule 4 and the passage from Query 31 as accounts of hypothetico-deductivism, we should read them as accounts of what I Bernard Cohen<\/a> called the \u2018Newtonian Style\u2019: a way of modelling the world in a series of increasingly complex and increasingly accurate idealisations (i.e. approximations that would hold exactly in certain specifiable circumstances).<\/p>\n

          On this blog, I have often discussed Newton\u2019s aim of certainty<\/a> and his corresponding claims to have achieved this aim.\u00a0 Newton\u2019s youthful aim of certainty places him in a position that is quite isolated from his contemporaries.\u00a0 Most of the experimental philosophers of the Royal Society thought it epistemically irresponsible to make such bold claims.\u00a0 Instead, they had more modest aims: obtaining highly probable theories.\u00a0 Rule 4, and the passage from Query 31, suggest that Newton eventually adopted a version of the hypothetico-deductivism preferred by his contemporaries.\u00a0 I have argued, however, that this is a misleading way of reading these passages.\u00a0 Newton uses rule 4, not to update the epistemic warrant of the theory, but its scope.<\/p>\n","protected":false},"excerpt":{"rendered":"

          Kirsten Walsh writes… In 1718, Newton published the second edition of Opticks.\u00a0 Query 23 was renamed Query 31, and in this query Newton expanded on his method of analysis.\u00a0 He wrote: \u201cIf no Exception occur from Ph\u00e6nomena, the Conclusion may […]<\/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":[224,16382,16383],"class_list":["post-2999","post","type-post","status-publish","format-standard","hentry","category-ideas","tag-newton","tag-query-31","tag-rule-4"],"_links":{"self":[{"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/posts\/2999","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=2999"}],"version-history":[{"count":0,"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/posts\/2999\/revisions"}],"wp:attachment":[{"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/media?parent=2999"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/categories?post=2999"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/tags?post=2999"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}