Blaise Pascal

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Blaise Pascal  began his academic career in the natural and applied sciences (fluids, calculating machines, geometry). He made important contributions to mathematics (‘Pascal’s triangle’, probability theory, philosophy of mathematics), and earned a reputation for his clarification of the notion of the vacuum demonstrated by Evangelista Toricelli. A true supporter of Jansenism, Pascal also authored several influential works on theology (Pensées, 1669). See: DSB, vol. 10, pp. 303–4; Adamson, 1995. For background on Jansenism, see Strayer, 2008. See: https://plato.stanford.edu/entries/pascal/.

In 1646, also Blaise Pascal refuted the traditional Aristotelian doctrine that nature abhors a vacuum and engaged himself in replicating and reconsidering Torricellian experiments by performing vacuum-in-a-vacuum experiments at the French Puy-de-Dôme (Garber, 1992, pp. 136–143).

In the plenist demonstration of proposition 3 (‘It involves a contradiction that there should be a vacuum’) of Part 2 of Spinoza's digest of René Descartes, the Dutch philosopher fully agrees with Descartes that space cannot be void of body and that the world is filled with extended matter:

By a vacuum is understood extension without corporeal substance (by D5), i.e. (by P2), body without body, which is absurd’.

In fine, Spinoza had already formulated his main ontological objection to the vacuum by 1663. Confidently, he writes to Henry Oldenburg in the letter of July 17/27 that Robert Boyle—critically in favour of the void as he was deploying evidence from his investigations by using his illustrious air-pump—considered the impossibility of the vacuum just a ‘Hypothesis’:

But I do not know why he [Boyle] calls the impossibility of a vacuum a Hypothesis, since it follows very clearly from the fact that nothing has no properties. And I am surprised that the Distinguished Gentleman doubts this, since he seems to maintain that there are no real accidents. I ask whether there would not be a real accident if there were Quantity without Substance?

Despite later strained efforts by Oldenburg to start a discussion about the void with Spinoza, he never returned to the subject in his correspondence. In Part 1 of the Ethica discussing God, Spinoza would again staunchly advocate the impossibility of the vacuum. In E1p15s, demonstrating that no corporeal substance is, or can be, composite, he argues against the thesis that the existence of a vacuum entails the existence of a property:

Truly, of things which are really distinct from one another, one can be, and remain in its condition, without the other. Since, therefore, there is no vacuum in nature (a subject I discuss elsewhere), but all its parts must so concur that there is no vacuum, it follows also that they cannot be really distinguished, i.e. corporeal substance, insofar as it is a substance, cannot be divided.

In fine, Spinoza simply endorses the impossibility of the void. Hence, his anti-vacuum argument shows that corporeal substance cannot have really distinct parts. In spite of his promise to bring up the subject later in the ‘Ethics’, the topic is not mentioned again in the work itself for reasons further unknown.