Joseph Priestley is one of the most celebrated chemists of all time because of his role in the discovery of oxygen. So highly was he regarded that in 1922 the American Chemical Society named their most prestigious medal ‘The Priestley Medal’.
Priestley was born in 1733 and died in 1804. Thus, he flourished in the latter decades of the era of early modern experimental philosophy and a survey of his writings reveals that he embraced experimental philosophy. Indeed, by the late eighteenth century the experimental approach to natural philosophy was virtually without a rival in Britain. When analysing his writings on natural philosophy there is no sense that he believed that experimental philosophy needed to be defended or justified at all. To be sure, one finds the usual rhetoric of experimental philosophy, such as his comment in his Experiments and Observations relating to various Branches of Natural Philosophy (London, 1779) that:
Speculation without experiment has always been the bane of true philosophy. (Preface, vii)
Yet when one turns to his Heads of Lectures on a Course of Experimental Philosophy (London, 1794) the term ‘Experimental Philosophy’ in the title is entirely unselfconscious. He opens Lecture I with a statement of the aim of the discipline:
The object of experimental philosophy is the knowledge of nature in general, or more strictly, that of the properties of natural substances, and of the changes of those properties in different circumstances. This knowledge can only be attained by experiment, or observation. (p. 1)
He goes on to mention one of the ‘rules of philosophizing’ in this discipline: ‘to admit no more causes than are necessary to account for the effects’ (p. 3). Of course, this is Newton’s first rule of philosophizing from the second edition of the Principia and it is hardly surprising that Priestley goes on to claim that given the ‘power of gravity’ ‘we are authorized to reject the Cartesian Vortices’ (ibid.).
One might, therefore, regard Priestley’s writings as not having anything to teach us about early modern experimental philosophy. And yet there is at least one point that is worth highlighting, for, Priestley was the second person to use the term ‘empiricism’ in the title of a book in English. The first was Francis Guybon in his An Essay concerning the Growth of Empiricism; or the Encouragement of Quacks, London, 1712 which was an attack on medical quacks.
Then in 1775 Priestley published a book entitled Philosophical Empiricism: containing Remarks on a Charge of Plagiarism respecting Dr H––. He had been attacked by the Irish physician Bryan Higgins who had accused him of plagiarism and Priestley defended himself, attacking many claims in Higgins’ lectures and concluding:
These and suchlike long-exploded, and crude notions (so many of which I believe were never thrown together into the same compass since the age of Aristotle or Cartesius) are delivered in a manner and phrase so quaint, and a tone so solemn and authoritative, as gives me an idea that I cannot express otherwise than by the term Philosophical Empiricism. (p. 59)
What is interesting here is that ‘empiricism’ is used as a pejorative and is loosely associated with Descartes! This all predates the Kantian Rationalism and Empiricism distinction –– the RED. It is even tempting to claim that it shows the inappropriateness of foisting the term ‘empiricism’ in its Kantian sense on eighteenth century thinkers when it already had strong currency in eighteenth-century English with an entirely different meaning.