{"id":2079,"date":"2012-02-20T22:00:32","date_gmt":"2012-02-20T10:00:32","guid":{"rendered":"https:\/\/blogs.otago.ac.nz\/emxphi\/?p=2079"},"modified":"2012-02-20T15:18:12","modified_gmt":"2012-02-20T03:18:12","slug":"hypotheses-versus-queries-in-newton%e2%80%99s-opticks","status":"publish","type":"post","link":"https:\/\/blogs.otago.ac.nz\/emxphi\/hypotheses-versus-queries-in-newton%e2%80%99s-opticks\/","title":{"rendered":"Hypotheses versus Queries in Newton\u2019s Opticks"},"content":{"rendered":"

Kirsten Walsh writes\u2026<\/strong><\/p>\n

A while ago<\/a> I argued that the queries in Newton\u2019s early optical papers are not hypotheses.\u00a0 Rather, they are empirical questions that may be resolved by experiment.\u00a0 In Newton\u2019s Opticks<\/em><\/a>, however, his queries become increasingly speculative \u2013 especially the famous \u2018Query 31\u2019.\u00a0 What should we make of this?\u00a0 Did Newton abandon his early distinction between hypotheses and queries?<\/p>\n

In his early optical papers, Newton explains that \u201cthe proper Method for inquiring after the properties of things is to deduce them from Experiments\u201d.\u00a0 Having obtained a theory in this way, one should proceed as follows:<\/p>\n

    \n
  1. specify queries that suggest experiments that will test the theory; and<\/li>\n
  2. carry out those experiments.<\/li>\n<\/ol>\n

    He tells us that hypotheses have a role in this procedure.\u00a0 They may be useful for: (a) suggesting further experiments, as the first step toward specifying queries; and (b) \u2018illustrating\u2019 the theory to assist understanding.<\/p>\n

    The queries in Newton\u2019s Opticks <\/em>have been much talked about, and often Newton has been accused of slipping hypotheses into his work under the guise of the more-respectable query.\u00a0 To examine this claim, I looked at the draft manuscripts* of Newton\u2019s Opticks<\/em>; in particular, \u201cThe fourth book concerning the nature of light & ye power of bodies to refract & reflect it\u201d (Add. 3970<\/a>, 337-8).<\/p>\n

    The draft begins, as many of the other books of Opticks<\/em> begin, with a list of observations, followed by numbered propositions.\u00a0 However, it contains little in the way of argument and virtually no discussion of experimental evidence.\u00a0 Shapiro <\/a>points out that this is because this is a draft of an outline or plan of a book; not a draft of the book itself.\u00a0 The propositions are things that Newton hoped<\/em> to prove.\u00a0 For example:<\/p>\n

      Prop. 1.\u00a0 The refracting power of bodies in vacuo is proportional to their specific gravities.
      \nProp. 2.\u00a0 The refracting power of two contiguous bodies is the difference of their refracting powers in vacuo.<\/ol>\n

      The draft contains a section entitled \u2018The conclusion\u2019, which contains five \u2018hypotheses\u2019.\u00a0 I am interested in \u2018Hypothesis 2\u2019:<\/p>\n

        As all the great motions in the world depend upon a certain kind of force (wch in this earth we call gravity) whereby great bodies attract one another at great distances: so all the little motions in ye world depend upon certain kinds of forces whereby minute bodies attract or dispell one another at little distances.<\/ol>\n
          How the great bodies of ye earth Sun moon & Planets gravitate towards one another what are ye laws of & quantities of their gravitating forces at all distance from them & how all ye motions of those bodies are regulated by those their gravities I shewed in my Mathematical Principles of Philosophy to the satisfaction of my readers: And if Nature be most simple & fully consonant to her self she observes the same method in regulating the motions of smaller bodies wch she doth in regulating those of the greater\u2026 The truth of this Hypothesis I assert not because I cannot prove it.\u00a0 But I think it very probable because a great part of the phaenomena of nature do easily flow from it wch seem otherways inexplicable\u2026<\/ol>\n

          I. Bernard Cohen<\/a> describes this as \u201ca \u2018whale\u2019 of an hypothesis\u201d \u2013 and he\u2019s right!\u00a0 When Newton started writing out this statement, he intended for it to be \u2018Proposition 18\u2019.\u00a0 But at some point, he has scratched out \u2018Prop 18\u2019, and re-branded it as \u2018Hypoth 2\u2019.\u00a0 There is no real semantic difference between a proposition and a hypothesis, but, for Newton, there is an epistemic difference.\u00a0 Propositions are things that he is able to assert as true.\u00a0 Hypotheses are things that he is unable to assert, because he does not have the evidence.\u00a0 Newton clearly hoped to assert Proposition 18.\u00a0 But as he started to explicate it, he must have realised that he couldn\u2019t prove it.\u00a0 Thus, he re-labelled it as a hypothesis.<\/p>\n

          When Newton abandoned the fourth book, and restructured the rest of his Opticks<\/em>, this \u2018Hypothesis 2\u2019 appears to have been re-worked to become \u2018Query 31\u2019 in Opticks<\/em>, 2nd<\/sup> edition (1717):<\/p>\n

            Have not the small Particles of Bodies certain Powers, Virtues, or Forces, by which they act at a distance, not only upon the Rays of Light for reflecting, refracting, and inflecting them, but also upon one another for producing a great Part of the Phaenomena of Nature?\u00a0 For it\u2019s well known, that Bodies act one upon another by the Attractions of Gravity, Magnetism, and Electricity; and these Instances shew the Tenor and Course of Nature, and make it not improbable but that there may be more attractive Powers than these.\u00a0 For Nature is very consonant and conformable to her self\u2026<\/ol>\n

            \"\"Here, there is an obvious semantic shift between hypothesis and query: the query is stated as a question.\u00a0 Some scholars have argued that this is the only <\/em>difference between hypotheses and queries: in the Opticks<\/em>, queries are simply Newton\u2019s way of getting around his self-imposed ban on hypotheses.\u00a0 I claim that there is more to the shift than this.\u00a0 Newton is using the semantic structure of the query to explore a possible future research program.\u00a0 The epistemic difference between the query and the hypothesis is similar to the epistemic difference between Popper\u2019s <\/a>falsifiable and unfalsifiable theories.\u00a0 The former is testable-in-principle, whereas the latter is not; and testability is a necessary condition of something becoming well-tested.<\/p>\n

            There is a difference between Newton\u2019s early queries and his later queries: the former are part of the process of justification; but the latter are part of the process of discovery.\u00a0 In a previous post<\/a> I noted that:<\/p>\n

              While Newton\u2019s [early] method of queries is experimental, it does not appear to be strictly Baconian. \u00a0For the Baconian-experimental philosopher, queries serve \u201cto provoke and stimulate further inquiry\u201d. \u00a0Thus, for the Baconian-experimental philosopher, queries are part of the process of discovery. \u00a0However, for Newton, queries serve to test the theory and to answer criticisms.\u00a0 Thus, they are part of the process of justification.<\/ol>\n

              The queries in Newton\u2019s later work seem closer to the Baconian tradition that inspired him.<\/p>\n

              That the themes of Hypothesis 2 and Query 31 appear in Rule 3 of Principia<\/em><\/a>, <\/em>raises questions about the status of Newton\u2019s \u2018Rules of Philosophising\u2019 and how we should interpret the re-branding of \u2018hypotheses\u2019 as \u2018rules\u2019 in later editions of Principia<\/em>.\u00a0 I’d love to hear what you think!<\/p>\n

               <\/p>\n

              * Recently, Cambridge University<\/a> put Newton\u2019s papers online, making it possible for those of us who live \u2018down under\u2019 to examine copies of many of Newton\u2019s manuscripts!<\/p>\n","protected":false},"excerpt":{"rendered":"

              Kirsten Walsh writes\u2026 A while ago I argued that the queries in Newton\u2019s early optical papers are not hypotheses.\u00a0 Rather, they are empirical questions that may be resolved by experiment.\u00a0 In Newton\u2019s Opticks, however, his queries become increasingly speculative \u2013 […]<\/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":[359,224,348,238],"class_list":["post-2079","post","type-post","status-publish","format-standard","hentry","category-ideas","tag-hypothesis","tag-newton","tag-optics","tag-queries"],"_links":{"self":[{"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/posts\/2079","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=2079"}],"version-history":[{"count":0,"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/posts\/2079\/revisions"}],"wp:attachment":[{"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/media?parent=2079"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/categories?post=2079"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/tags?post=2079"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}