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The demise of Spinozism and the rise of Dutch experimental philosophy

A guest post by Wiep van Bunge.

Wiep van Bunge writes…

Rienk Vermij has demonstrated quite convincingly that the first Dutch Newtonians were actively engaged in countering the threat Spinoza posed (Vermij 2003). A crucial moment in the simultaneous demise of Spinozism and the rise of experimental philosophy was Bernard Nieuwentijt’s publication, in 1715, of his famous Het regt gebruik der wereldbeschouwingen – translated into English, French and German. Nieuwentijt specifically marked out Spinoza’s atheism as his main target, inspiring many dozens of countrymen and many others abroad to discern the providential reign of a supernatural Creator, who was not to be identified with Nature in the way the Spinozists had been doing for several decades.

More interesting, however, is his posthumous Gronden van zekerheid, in which he further developed a number of comments on mathematics made by one of Spinoza’s earliest critics, the linguist and philosopher Adriaen Verwer in his 1683 refutation of Spinoza’s Ethics. Verwer had warned his readers against Spinoza’s confusion of entia realia, things that really exist, and entia rationis, things we can talk about coherently but which are only supposed to exist even though we are able to conceive of them clearly and distinctly. Spinoza’s fundamental error, according to Verwer, consisted in supposing that once a clear and distinct idea has been formed, the ideatum conceived of in the idea really exists (Verwer 1683; 1–5).

In Gronden van zekerheid Nieuwentijt first elaborates on the distinction between ‘imaginary’ (denkbeeldige) and ‘realistic’ (zakelijke) mathematics, that is between a mathematics concerned with abstract notions without any corresponding objects in reality, and a mathematics concerned with objects the reality of which has been established by experience. Thus Nieuwentijt attempts to ensure that the use of mathematical reasoning is reserved for the behaviour of natural, observable objects. After having demonstrated the benefits of a ‘realistic’ use of mathematics, Nieuwentijt in the fourth part of Gronden van zekerheid accuses Spinoza of being merely an ‘imaginary’ mathematician, who just made it look as if his abstract metaphysics had anything to do with the real world. In reality, or so Nieuwentijt felt, Spinoza was only talking about his own, private ideas. What is worse, Spinoza consciously refused to acknowledge the need to ascertain the correspondence of these ideas to any external reality, as is evident, Nieuwentijt continued, from Spinoza’s conception of truth. Neither was he prepared to check the truth of his ‘deductions’ against any empirical evidence, which led him to preposterous conclusions, such as regarding the human intellect as being a part of God’s infinite intellect as well as an idea of an existing body (Nieuwentijt 1720: 244ff).

Throughout Gronden van zekerheid Nieuwentijt points to the obvious alternative to Spinoza’s ‘figments of the imagination’: the experiential ‘realistic mathematics’ adopted by the Royal academies of Britain, France and Prussia as well as by countless serious scientists across Europe. Philosophy, Nieuwentijt contended in the fifth and final part of his book, should become a ‘realistic metaphysics’ (sakelyke overnatuurkunde), which rests on the same foundations that realistic mathematicians build on: faith in the revealed Word of God and experience, to which he adds that philosophers are often best advised to suspend judgment because we simply lack the data necessary for answering many of the question traditionally raised by metaphysicians (Nieuwentijt 1720: 388ff). Newton, ‘the mathematical Knight’, had shown the way by setting up experiments in order to confirm the truth of conclusions arrived at by means of deduction and by making sure that the general principles from which these conclusions derived were the result of ‘empirical’ induction (Nieuwentijt 1720: 83–84; 188 ff). In addition, Nieuwentijt was happy to confirm that Newton’s work clearly established the providential reign of the Creator over His creation, making it an ideal weapon in the fight against atheism (Nieuwentijt 1720: 228).

It would seem, then, that in Nieuwentijt’s eyes, and Verwer appears to have been of the same opinion, Spinozism was actually a philosophical instance of ‘enthusiasm’ – not unlike the German theologian Buddeus’ earlier suggestion (Buddeus 1701: 15–16). Both were appalled to read that according to Spinoza ideas were true to the extent that he himself felt them to be true, instead of checking their correspondence to the world as we know it. Thus Nieuwentijt continued an Aristotelian and humanist tradition according to which ‘contemplative philosophy’ represented a type of ‘philosophical enthusiasm’ (Heyd 1995: Ch. 4).


Buddaeus, I.F., Dissertatio philosophica de Spinozismo ante Spinozam (Halle, 1701).

Heyd, Michael, ‘Be Sober and Reasonable’. The Critique of Enthusiasm in the Seventeenth and Early Eighteenth Centuries (Leiden, 1995).

Nieuwentijt, Bernard, Het regt gebruik der wereldtbeschouwingen, ter overtuiginge van ongodisten en en ongelovigen aangetoont (Amsterdam,1715).

–, Gronden van zekerheid, of de regte betoogwyse der wiskundigen, So in het denkbeeldige als in het het zakelyke (Amsterdam, 1720).

Vermij, Rienk, ‘The Formation of the Newtonian Natural Philosophy. The Case of the Amsterdam Mathematical Amateurs’, The British Journal for the History of Science 36 (2003), 183–200.

Verwer, Adriaen,’t Mom-Aensicht der atheisterij afgerukt door een verhandeling van den aengeboren stand der menschen (Amsterdam, 1683).


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