{"id":3500,"date":"2014-01-20T16:00:35","date_gmt":"2014-01-20T04:00:35","guid":{"rendered":"https:\/\/blogs.otago.ac.nz\/emxphi\/?p=3500"},"modified":"2014-01-20T10:18:23","modified_gmt":"2014-01-19T22:18:23","slug":"observation-and-experiment-in-the-opticks-a-baconian-interpretation","status":"publish","type":"post","link":"https:\/\/blogs.otago.ac.nz\/emxphi\/observation-and-experiment-in-the-opticks-a-baconian-interpretation\/","title":{"rendered":"Observation and Experiment in the Opticks: A Baconian Interpretation"},"content":{"rendered":"

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

In a recent post<\/a>, I considered Newton\u2019s use of observation and experiment in the Opticks<\/em>.\u00a0 I suggested that there is a functional <\/em>(rather than semantic) difference between Newton\u2019s \u2018experiments\u2019 and \u2018observations\u2019.\u00a0 Although both observations and experiments were reports of observations involving intervention on target systems and manipulation of independent variables, experiments offered individual, and crucial, support for particular propositions, whereas observations only supported propositions collectively.<\/p>\n

At the end of the post, I suggested that, if we view them as complex, open ended series\u2019 of experiments, the observations of books 2 and 3 look a lot like what Bacon <\/a>called \u2018experientia literata\u2019<\/em>, the method by which natural histories were supposed to be generated.\u00a0 In this post, I\u2019ll discuss this suggestion in more detail, following Dana Jalobeanu\u2019s <\/a>recent work on Bacon\u2019s Latin natural histories and the art of \u2018experientia literata<\/em>\u2019.<\/p>\n

The \u2018Latin natural histories\u2019 were Bacon\u2019s works of<\/em> natural history, as opposed to his works about<\/em> natural history.\u00a0 A notable feature of Bacon\u2019s Latin natural histories is that they were produced from relatively few \u2018core experiments\u2019.\u00a0 By varying these core experiments, Bacon generated new cases, observations and facts.\u00a0 The method by which this generation occurs is called the art of \u2018experientia literata\u2019.\u00a0 <\/em>\u00a0Experientia literata<\/em> (often referred to as \u2018learned experience\u2019) was a late addition to Bacon\u2019s program, developed in De Augmentis scientiarum<\/em><\/a> (1623).\u00a0 It is a tool or technique for guiding the intellect.\u00a0 By following this method, discoveries will be made, not by chance, but by moving from one experiment to the next in a guided, systematic way.<\/p>\n

The following features were typical of the experientia literata<\/em>:<\/p>\n

    \n
  1. The series of observations was built around a few core experiments;<\/li>\n
  2. New observations were generated by the systematic variation of experimental parameters;<\/li>\n
  3. The variation could continue indefinitely, so the observation sequence was open-ended;<\/li>\n
  4. The experimental process itself could reveal things about the phenomena, beyond what was revealed by a collection of facts;<\/li>\n
  5. The trajectory of the experimental series was towards increasingly general facts about the phenomena; and<\/li>\n
  6. The results of the observations were collated and presented as tables. \u00a0These constituted the \u2018experimental facts\u2019 to be explained.<\/li>\n<\/ol>\n

    Now let\u2019s turn to Newton\u2019s observations.\u00a0 For the sake of brevity, my discussion will focus on the observations in book 2 part I of the Opticks<\/em>, but most of these features are also found in the observations of book 2 part IV, and in book 3 part I.<\/p>\n

    \"\"

    Figure 1 (Opticks, book 2 part I)<\/p><\/div>\n

    The Opticks<\/em> book 2 concerned the phenomenon now known as \u2018Newton\u2019s Rings\u2019<\/a>: the coloured rings produced by a thin film of air or water compressed between two glasses.\u00a0 Part I consisted of twenty-four observations.\u00a0 Observation 1 was relatively simple: Newton pressed together two prisms, and noticed that, at the point where the two prisms touched, there was a transparent spot.\u00a0 The next couple of observations were variations on that first one: Newton rotated the prisms and noticed that coloured rings became visible when the incident rays hit the prisms at a particular angle.\u00a0 Newton progressed, step-by-step, from prisms to convex lenses, and then to bubbles and thin plates of glass.\u00a0 He varied the amount, colour and angle of the incident light, and the angle of observation.\u00a0 The result was a detailed, but open ended, survey of the phenomena.\u00a0 Part II consisted of tables that contained the results of part I.\u00a0 These constituted the experimental facts to be explained in propositions in part III.\u00a0 In part IV, Newton described a new set of observations, which built on the discussions of propositions from part III.<\/p>\n

    When we consider Newton\u2019s observations alongside Bacon\u2019s experientia literata<\/em>, we notice some common features.<\/p>\n

    Firstly, the series of observations was built around the core experiment involving pressing together two prisms to observe the rings that appeared.<\/p>\n

    Secondly, new observations were generated by the variation of experimental parameters: i.e. new observations were generated, first by varying the obliquity of the incident rays, then by varying the glass instruments, then by varying the colour of the incident light, and so on.<\/p>\n

    Thirdly, the sequence of observations was open-ended.\u00a0 Newton could have extended the sequence by varying the medium, or some other experimental parameter.\u00a0 Moreover, at the end of the sequence, Newton noted further variations to be carried out by others, which might yield new or more precise observations.<\/p>\n

    Fourthly, the experimental process itself revealed things about the phenomenon, beyond what was revealed by a collection of facts.\u00a0 For example, in observation 1, Newton noticed that increasing the pressure on the two prisms produced a transparent spot.\u00a0 The process of varying the pressure, and hence the thickness of the film of air between the two prisms, suggested to Newton a way of learning more about the phenomenon of thin plates.\u00a0 He realised he could quantify the phenomenon by introducing regularly curved object glasses, which would make the variation in thickness regular, and hence, calculable.<\/p>\n

    Fifthly, the trajectory of the experimental series was towards increasingly general facts about the phenomenon. \u00a0Newton began by simply counting the number of rings and describing the sequence of colours under specific experimental parameters.\u00a0 But eventually he showed that the number of rings and their colours was a function of the thickness and density of the film.\u00a0 Thus, he was able to give a much broader account of the phenomenon.<\/p>\n

    Finally, these general results were collated and presented as tables in part II.\u00a0 Thus, the tables in part II constituted the facts to be explained by propositions in part III.<\/p>\n

    Many commentators have emphasised the ways that Newton deviated from Baconian method.\u00a0 However, when viewed in this light, book 2 of the Opticks<\/em> provides a striking example of conformity to the Baconian method of natural history: Newton led the reader from observations in part I, to tables of facts in part II, to propositions in part III.\u00a0 Moreover, it ended with a further series of observations in part IV, emphasising the open-endedness of the art of experientia literata<\/em>.<\/p>\n

    In contrast to the observations in book 2, Newton\u2019s experiments in book 1 look like Bacon\u2019s \u2018instances of special power\u2019, which are particularly illuminating cases introduced to provide support for specific propositions.\u00a0 I\u2019ll discuss this next time.\u00a0 For now, I\u2019d like to hear what our readers think of my Baconian interpretation of Newton\u2019s observations.<\/p>\n","protected":false},"excerpt":{"rendered":"

    Kirsten Walsh writes\u2026 In a recent post, I considered Newton\u2019s use of observation and experiment in the Opticks.\u00a0 I suggested that there is a functional (rather than semantic) difference between Newton\u2019s \u2018experiments\u2019 and \u2018observations\u2019.\u00a0 Although both observations and experiments were […]<\/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":[289,276,349,224,16410,16419],"class_list":["post-3500","post","type-post","status-publish","format-standard","hentry","category-ideas","tag-baconian","tag-experiment","tag-natural-history","tag-newton","tag-observation","tag-opticks"],"_links":{"self":[{"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/posts\/3500","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=3500"}],"version-history":[{"count":0,"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/posts\/3500\/revisions"}],"wp:attachment":[{"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/media?parent=3500"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/categories?post=3500"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.otago.ac.nz\/emxphi\/wp-json\/wp\/v2\/tags?post=3500"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}