I examine the (mediated) correspondence between Spinoza and Robert Boyle concerning the latter’s account of fluidity and his experiments on reconstitution of niter in the light of the epistemology and doctrine of method contained in the Treatise on the Emendation of the Intellect. I argue that both the Treatise and the correspondence reveal that for Spinoza, the proper method of science is not experimental, and that he accepted a powerful under-determination thesis. I argue that, in contrast to modern versions, Spinoza’s (...) form of naturalism was a highly rationalist and anti-empirical one. I conclude with a brief account of the value of experience and experimentation for Spinoza’s scientific method. (shrink)

In this paper, I argue for a novel reading of Spinoza’s position in his exchangewith Boyle about Boyle’s experiment with nitre. Boyle claimed to have shownthrough experiments that nitre ceased to be nitre after heating. Spinozadisagreed and proposed the alternative hypothesis that nitre has changed itsstate and not its nature. Spinoza’s position was construed in the literature asrational scepticism denying that experiments can yield knowledge ofessences because all sensory experience is underdetermined and open tomultiple interpretations. I argue for an alternative (...) reading of Spinoza’sposition which focuses on Bacon’s notion of crucial instance. According tothis reading, Spinoza did not deny the possibility of knowing byexperimentation whether nitre has changed its nature, he asked for a crucialinstance, i.e. an experiment that would refute the hypothesis that nitre haschanged merely its state. Spinoza’s argumentative strategy shows that,contrary to the mainstream reading, the representational content of sensoryideas can be determined even if it does not represent the essence of theobject: we can know with absolute, rather than merely moral, certaintywhether nitre ceased to be nitre without knowing what nitre is. (shrink)