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Monthly Archives: September 2014

James Bradley’s Lectures on Experimental Philosophy

Peter Anstey writes …

In my last post I discussed the astronomer James Bradley who taught experimental philosophy in Oxford from 1729 until 1760. Since then I have examined Bradley’s extant lectures in the Bodleian Library, Oxford.

One of the most interesting features of the lectures is the manner in which the distinction between experimental and speculative philosophy is presented at the very beginning of his opening lecture. Bradley commences with a general reference to the laws of nature:

/1/ … these are no otherwise to be discovered than by experiments & observation & examining the Phaenomena & finding from them by what /2/ laws their motions are ordered & regulated. which is properly the Business & scope of Natural & Experimental Philosophy. (Bodleian Library MS Bradley 1, p. 1 (Used with permission of Bodleian Libraries, University of Oxford)

This view of natural philosophy is interesting in so far as it places laws of nature and experiment to the fore in a manner that was not possible before the advent of Newton’s Principia. Bradley continues:

But then our principal endeavour must be to learn the true & real manner in which the operations of Natur are actually performd & not content ours[elves] with framing Hypoth[eses] to explain how such Phaenom[ena] may be perform’d tis on this account that Reasoning much from Hypotheses in Natural Phil[osophy] is apt to lead people into mistakes and there is no likelier a method to avoid error than having recourse to experiments & trials (Bodleian Library MS Bradley 1, p. 2 (Used with permission of Bodleian Libraries, University of Oxford)

Note here the rhetoric of experimental philosophy: the warning against ‘framing Hypotheses’ which can lead to error, and the emphasis on experiment and observation. Bradley then expresses a form of fallibilism in his claims about the epistemic status of knowledge acquired by the method of ‘experiments & trials’:

/3/ Tho this is no doubt the most likely method of coming at the truth yet even in this manner of proceeding we must not expect to meet with Proof in Natural Philosophy so absolutely convincing as in pure mathematics because the Ideas we have to do with in Mathematics are the Productions of the mind itself & therefore we may have a more full adequate knowledge of them than of those we have in natural Philosophy which being fram’d from things without us they may not be just & consequently our deductions & reasonings about these may be liable to some uncertainty & leave some scruple upon the mind. (Bodleian Library MS Bradley 1, p. 3 (Used with permission of Bodleian Libraries, University of Oxford)

Bradley is honest in his claim that one should not expect mathematical certainty in matters of experimental natural philosophy. Yet he also believes that there are measures that one can take to assure us that our inferences from experiments are secure:

In order to remove all scruple as much as possible & that the mind may assent to the conclusions drawn from facts & experiments in searching into the operations of nature Sir I. Newton lays down the following Rules of Arguing in Natural Philosophy. (Bodleian Library MS Bradley 1, p. 3 (Used with permission of Bodleian Libraries, University of Oxford)

He then summarises the four rules of philosophising that Newton first published in the second edition of the Prinicpia.

What Bradley is providing in his very first lecture is a methodological statement that reveals his conception of natural philosophy and the means by which one acquires the knowledge of nature. This is what generations of students were taught at Oxford when they enlisted in his courses in the Old Ashmolean Museum. Now there are some scholars who question the value of the experimental/speculative distinction as terms of reference for understanding early modern British natural philosophy. It is necessary, however, to ask what more it would take for the ESD to be taken seriously than a lecture on natural philosophy that was repeated at least 79 times over twenty-one years to inquisitive university students at Oxford University who were paying to be taught experimental philosophy by an eminent practitioner. This is not empty ‘method talk’, this is not the RED, the rationalism/empiricism distinction, in disguise. These are the actors’ terms of reference, and they are not in polemical writings, or in promotional puffs prefacing controversial works in natural philosophy, but in ordinary undergraduate lectures.