{"id":3275,"date":"2013-09-02T16:00:46","date_gmt":"2013-09-02T04:00:46","guid":{"rendered":"https:\/\/blogs.otago.ac.nz\/emxphi\/?p=3275"},"modified":"2013-09-02T17:35:04","modified_gmt":"2013-09-02T05:35:04","slug":"newtons-phenomena","status":"publish","type":"post","link":"https:\/\/blogs.otago.ac.nz\/emxphi\/newtons-phenomena\/","title":{"rendered":"Newton’s ‘Phenomena’ continued…"},"content":{"rendered":"

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

In my last post<\/a>, I considered the phenomena in book 3 of Newton\u2019s Principia<\/em>. \u00a0Newton\u2019s decision to label these propositions \u2018phenomena\u2019 is puzzling, as they do not seem to fit any standard definition of the term.\u00a0 In this post, I\u2019ll consider Bogen & Woodward\u2019s (1988)<\/a> distinction between data, phenomena and theories, and suggest that it sheds light both on Newton\u2019s use of \u2018phenomena\u2019 and on the connection between his methodology in Opticks <\/em>and Principia.<\/em><\/p>\n

Bogen & Woodward (B&W) have argued for a 3-level picture of scientific theories in which:<\/p>\n

    \n
  1. \u2018Data\u2019 are records produced by measurement and experiment that serve as evidence or features of phenomena.\u00a0 E.g. bubble chamber photographs, and patterns of discharge in electronic particle detectors.<\/li>\n
  2. \u2018Phenomena\u2019 are features of the world that in principle could recur under different contexts or conditions.\u00a0 E.g. weak neutral currents, and the decay of a proton.<\/li>\n
  3. \u2018Theories\u2019 are explanations of the phenomena.<\/li>\n<\/ol>\n

    B&W argue that theories explain phenomena, but not data. \u00a0Data usually reflect many causal influences besides the explanatory target, while phenomena typically reflect single, or small, manageable numbers of causal influences.\u00a0 For example, General Relativity explains the phenomenon of bending light, but doesn\u2019t explain the workings of the cameras, optical telescopes, etc. that causally influence the data.<\/p>\n

    Can we characterise Newton\u2019s phenomena in terms of these three levels of theory?\u00a0 Let\u2019s consider phenomenon 1:<\/p>\n

      “The circumjovial planets, by radii drawn to the centre of Jupiter, describe areas proportional to the times, and their periodic times \u2013 the fixed stars being at rest \u2013 are as the 3\/2 powers of their distances from that centre.”<\/ol>\n

      In his discussion of this phenomenon Newton explained, \u201cThis is established from astronomical observations.\u201d\u00a0 He provided the following table:<\/p>\n

      \"\"These observations are not data in the \u2018pure\u2019 sense that B&W discuss.\u00a0 Rather, they are generalisations: average distances and calculated periods of orbit.\u00a0 Moreover, the bottom row contains the average distances calculated from the period and the Harmonic rule (that the periods are as the 3\/2 power of the semidiameters of their orbits).\u00a0 These calculations illustrate the \u2018fit\u2019 between the expected distance and the observed distance. \u00a0Nevertheless, they provide a good example of how we might get from a set of data to a phenomenon.\u00a0 So perhaps we can think of them as \u2018data\u2019 in a methodological sense: they are records from which <\/em>phenomenal patterns can be drawn.<\/p>\n

      I have another reason for considering these calculations \u2018data\u2019 in B&W\u2019s sense of the term.\u00a0 In his discussion of phenomenon 1, Newton indicated that these calculations reflect a number of causal influences besides gravity.\u00a0 For instance, he explained that the length of the telescope affected the measurement of Jupiter\u2019s diameter, because<\/p>\n

        \u201cthe light of Jupiter is somewhat dilated by its nonuniform refrangibility, and this dilation has a smaller ratio to the diameter of Jupiter in longer and more perfect telescopes than in shorter and less perfect ones.\u201d<\/ol>\n

        This is a nice illustration of B&W\u2019s notion of the shift from <\/em>data to phenomena.\u00a0 By attending to his theory about telescopes, Newton was able to manipulate the data to control for distortion.<\/p>\n

        Now let\u2019s consider the role of phenomenon 1 in Principia<\/em>.\u00a0 Phenomenon 1 is employed (in conjunction with proposition 2 or 3, book 1, and corollary 6 to proposition 4, book 1) to support proposition 1, theorem 1, book 3:<\/p>\n

          \u201cThe forces by which the circumjovial planets are continually drawn away from rectilinear motions and are maintained in their respective orbits are directed to the centre of Jupiter and are inversely as the squares of the distances of their places from that centre.\u201d<\/ol>\n

          This theorem doesn\u2019t contain any information about the sizes or positions of the satellites of Jupiter, or about the workings of telescopes.\u00a0 So, while it explains the phenomenon, it gives no direct explanation of the data. \u00a0This suggests that, in the Principia<\/em>, data and phenomena are methodologically distinct.<\/p>\n

          B&W\u2019s distinction between \u2018data\u2019 and \u2018phenomena\u2019 reveals two methodological features of Newton\u2019s phenomena:<\/p>\n

          Firstly, Newton\u2019s phenomena are explananda, but not appearances.\u00a0 Traditionally, \u2018phenomenon\u2019 seems to have been synonymous with both \u2018appearance\u2019 and \u2018explanandum\u2019.\u00a0 For example, the ancient Greeks were concerned to construct a system that explained and preserved the motions of the celestial bodies as they appeared to terrestrial observers.\u00a0 2000 years later, Galileo and Cardinal Bellarmine argued over which system, heliocentric or geocentric, provided a better fit and explanation of these appearances. \u00a0This suggests that, traditionally, there was no real difference between phenomena and data.\u00a0 For Newton, however, these come apart.\u00a0 The six phenomena of Principia <\/em>describe the motions of celestial bodies, but not as they appear to terrestrial observers.\u00a0 In this sense, they are not appearances, but they do require an explanation.<\/p>\n

          Secondly, this reveals a continuity in Newton\u2019s methodology. \u00a0The point <\/em>of Newton\u2019s articulation of \u2018phenomena\u2019 in Principia <\/em>is the same as his experiments in Opticks<\/em>.\u00a0 Both identify and isolate a pattern or regularity.\u00a0 In the Opticks<\/em>, Newton isolated his explanatory targets by making observations under controlled, experimental conditions. \u00a0In Principia<\/em>, Newton isolated his explanatory targets mathematically: from astronomical data, he calculated the motions of bodies with respect to a central focus. \u00a0Viewed in this way, Newton\u2019s phenomena and experiments are different ways of achieving the same thing: isolating explananda.<\/p>\n

          These considerations are admittedly speculative, so I\u2019m keen to hear what our readers think.\u00a0 Does this look like a good way of characterising Newton\u2019s phenomena?<\/p>\n","protected":false},"excerpt":{"rendered":"

          Kirsten Walsh writes… In my last post, I considered the phenomena in book 3 of Newton\u2019s Principia. \u00a0Newton\u2019s decision to label these propositions \u2018phenomena\u2019 is puzzling, as they do not seem to fit any standard definition of the term.\u00a0 In […]<\/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":[10582,226,224,16404],"class_list":["post-3275","post","type-post","status-publish","format-standard","hentry","category-ideas","tag-data","tag-experimental-philosophy","tag-newton","tag-phenomena"],"_links":{"self":[{"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/posts\/3275","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=3275"}],"version-history":[{"count":0,"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/posts\/3275\/revisions"}],"wp:attachment":[{"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/media?parent=3275"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/categories?post=3275"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/tags?post=3275"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}