Guest post by Alberto Vanzo from the Early Modern Experimental Philosophy Project in Otago, New Zealand

In the last post of his interesting series on early modern Aristotelian views on experience, Stefan compares some of their views with the views of early modern experimental philosophers. Stefan distinguishes between two ways of spelling out the ESD (that is, the distinction between experimental and speculative philosophy): as a disciplinary distinction between an empirical and a theoretical part of philosophy, or as a methodical distinction between two antithetical ways of practising philosophy. As Stefan argues, the former distinction can be found in late renaissance Aristotelianism. However, the early modern thinkers who called themselves “experimental philosophers” typically understood the ESD to be a distinction between two antithetical methods. For instance, Locke’s adversary John Sergeant writes in 1696:

“The METHODS which I pitch upon to examine, shall be of two sorts, viz. that of Speculative, and that of Experimental Philosophers; The Former of which pretend to proceed by Reason and Principles; the Later by Induction; and both of them aim at advancing Science.”

Experimental natural philosophers claimed that we should refrain from proceeding “by Reason and Principles”, as they took the Aristotelians to be doing. As John Dunton writes in The-Young-Students-Library of 1692,

“We must consider, the distinction we have made of Speculative and Experimental, and, as much as possible, Exclude the first, for an indefatigable and laborious Search into Natural Experiments, they being only the Certain, Sure Method to gather a true Body of Philosophy, for the Antient Way of clapping up an entire building of Sciences, upon pure Contemplation, may make indeed an Admirable Fabrick, but the Materials are such as can promise no lasting one.”

Similar statements could be found outside England, for instance in Diderot’s Thoughts on the Interpretation of Nature of 1754.

To be sure, some early modern authors distinguished between empirical (or experimental) and theoretical (or speculative) disciplines. For instance, Leibniz and Wolff both distinguish between empirical and rational physics. They are similar to some Aristotelians in that they think that natural philosophy relies on a priori, demonstrative reasonings alongside observations and experiments. They endeavour, to use Leibniz’s curious mix of Latin and German, “Theoricos Empiricis felici connubio zu conjungiren”: “to unite in a happy wedding theoreticians and observers”. However, Leibniz can be hardly called an experimental philosopher, and I would argue that Wolff – although he called his system philosophia universalis experimentalis – was at best an unorthodox experimental philosopher. The general trend was to contrast experiments and observations with hypotheses, conjectures, and demonstrative reasonings.

Experience, Natural Histories, and the Foundations of Natural Philosophy

As Stefan notes, the Baconian “‘hunt’ for 'fact’, namely 'nuggets of experience detached from theory’ […] is fully compatible with early modern Aristotelian theories of experience.” Admittedly, some forms of Aristotelianism were not as hostile to the projects of experimental philosophers as the latter suggested. Nevertheless, it seems to me that there is a fundamental difference between the function that experimental philosophers assigned to natural histories and the role that experience had for Andreas, Javellus, Fonseca, or Suarez.

Let me recall their views with some quotes from Stefan’s posts. For Andreas, “To grasp the content of a principle is an achievement of the intellect propria virtute”. “For knowledge of conclusions, again, experience may be helpful, but it is no precondition.” For Fonseca, experience “serves only to prevent error, but seems to have no independent justificatory function.” For Suarez, “the relevance of experience for knowledge is purely 'psychological’”, rather than epistemological. Javellus places more importance on experience. In his view, experience “serves as the indispensable starting point for scientific inquiry, and it is required in order to confirm the conclusions drawn in this inquiry”. However, the results of that inquiry will only be science if, say, “the purgative power of rhubarb is deduced from more general principles”.

Andreas’s, Fonseca’s, Suarez’s and Javellus’s views are quite different. What do they have in common? A feature that they all share is that none of them regards experience as a source of justification for natural-philosophical claims. Even Javellus, who assigns the greatest importance to experience, holds that science relies on demonstrative reasonings from principles. By contrast, experimental philosophers advocated an extensive and systematical recourse to experience because they regarded it as the source of justification for natural-philosophical claims and theories. Baconian natural histories were introduced as an “experimental” alternative to the “speculative” demonstrative reasonings upon which the Aristotelians relied. In fact, they adopted a new, Baconian form of natural history that differed from the traditional natural history that was known to the early modern Aristotelians. Boyle and Hooke also developed a philosophy of experiment, rather than a set of reflections on experience in general. The epistemological role of experience, natural histories, and experiments as sources of justification for natural philosophical claims appears to me to be, to use Stefan’s terms, “an area of fundamental disagreement between Aristotelians and the anti-Aristotelian novatores”.

As Stefan suggests, another area of disagreement may concern the role of mathematics. I am no expert in seventeenth century philosophy of mathematics and would love to hear what you readers think on this or on any other aspect of the relations between early modern Aristotelians and experimental philosophers.