Was René Descartes a Cartesian? Probably not; at least not to the extent that some caricatural reduction of his thinking, i. e. Cartesianism, would let us believe. Unable to demonstrate it in this short paper, we will try to indicate a few leads to advocate for his innocence. “Advocate” and “innocence” because it seems that Descartes often is literally accused of simplistic Cartesianism. So, we intend to show that he may be responsible, but that he is not guilty. To get there, we will start with the most general topics, then go to the particular ones, specially to the so-called denounced “bifurcation”.

Then we will briefly look at the critics Newton may unfairly be subject to.

Was Descartes a Cartesian?

17th Century Context.

For any historical subject, as we all know, understanding the context is essential. We are in the 17th century with renewed literature: Cervantes († 1616), Shakespeare († 1616), Molière († 1673); renewed music: Monteverdi († 1643), Purcell († 1695), renewed architecture (emblematically the château de Versailles), renewed societies: French absolutism (Louis XIII, † 1643), English revolution (Cromwell, † 1658).

No surprise that science (Kepler, † 1630; Galileo, † 1642; Pascal, † 1662; Huygens, † 1695; Newton, † 17271; etc.) and philosophy (Francis Bacon, † 1626; Descartes, † 1650; Spinoza, † 1677; Hobbes, † 1679; Locke, † 1704; Leibniz, † 1716; etc.) develop new, not to say revolutionary, ideas.

On the side of technics, this is very much the time of new machines, whether automatons, steam turbine & machines (Branca, Papin, Savery), pneumatic machines (von Guericke, Boyle), machines for continuous production of static electricity (von Guericke), pumping machines (Marly), not to forget the mechanical calculator (Schickard, Pascal)…

In short, this is an era of scientific novelty and machinery, i.e. of mechanics (Galileo, Descartes, Newton) preparing the universal determinism of the 18th century (d’Holbach, Laplace) and the scientism of the 19th century, while, at the same time, it marks a relative rupture with prior excessively speculative conceptions (Scholasticism). A “relative rupture”, because, as example and as very few know, the Copernic († 1543) cosmologic system was taught as an hypothesis by the Catholic Church, before Galileo was even born (in 1564).

Science or Philosophy?

If philosophy is separated from science in most minds of that time, the fact is that many famous philosophers were indeed mathematicians and physicists as well (Huygens, Newton, Descartes, Pascal, Leibniz). This means that we need to make sure whether we address their scientific conceptions or their philosophical (or even metaphysical) ones.

Yet, in the case of Descartes, quite uniquely to such extend, philosophy and science are particularly mixed (but not all mixed up!). How much is that? His mathematical mind let him create the analytic geometry and the basis for the calculus (further developed by Newton and Leibniz) and, in physics, let him create geometric optics, some of dynamics and find the Snell-Descartes low of refraction — not to forget an early form of the law of conservation of mechanical momentum (which will be later rectified by Huygens and others).

Now, if Descartes works, written from the age of 36 to his death at 53, rather is philosophical, this is because, when Galileo is condemned, he refrains from publishing his book The World or Treatise on the Light2 —dealing with heliocentrism, Corpuscularianism (a sort of atomism) and biology— and abandon physics for philosophy. Yet, he will include some revised chapters of that scientific book into his philosophical ones. Thus, the threefold philosophical corpus begins with a method of science looking for giving a mathematical certainty to any knowledge and, as such, founding a mathesis universalis (universal science): that is the Discourse on the Method3. However, if not at all empiricist (unlike his contemporary Francis Bacon or Locke), still he recommends a praxis, per which the proper knowledge of elements and bodies could be utilized by men “to become like masters and owners of nature” (6th part of the Discourse). It is in the second opus, Meditations on First Philosophy4, where we further find the famous Cogito, the res extensa (“extended thing”) and the res cogitans (“thinking thing”), as well as the various proofs of God’ existence. The third one, Principles of Philosophy5, proposes to look for the truth with the only reason and without the faith, inaugurally introduces the necessity of “general laws”6, and sets philosophy at the top of a tree of science, whose roots are metaphysics, the trunk physics and the three main sciences: medicine, mechanics and ethics, the comprehensive knowledge of which is essential to philosophy and to the Sophia it aims at.

As we see, we have here, at the end, a philosophical approach necessarily rooted in the understanding of where science stands (at a given time). Whitehead († 1947), mathematician and physicist too, will share the same conception of philosophy, but this will take place after evolutionism, relativity and quantum physics arousal. In these sciences, things happen, arise, proceed, evolve… so his metaphysics will be some “organism philosophy” or “process philosophy”. But is this thus still pure philosophy, from someone who recognized himself as a profane?

Mistakes or Misunderstanding?

Cartesianism (i. e. Descartes followers) certainly is one of the main sources of confusion, but not the only one.

1. Starting with the Cogito, it will suffice to mention how Kant († 1804) himself completely misread the Cogito. Admittedly, the out of context picked up formula cogito, ergo sum effectively translate into “I think, therefore I am”, but it misses the Cartesian experience of existing and hence of being thinking, which is stated right in the same sentence: “…Having noticed that there is nothing at all in this: I think, therefore I am, which grants that I say the truth, except that I clearly see that to think one must be…” (Discourse on the Method).

So one could say, strictly respecting Descartes thinking, that: I think, because I am, but, then, how and why to hierarchize existing, thinking and saying it, when such performative affirmation requires just the three of them together? This is because the Cogito is not “thought thinking” but “thinking thought” (thinking in act); therefore existence is in it: “…One must finally conclude and maintain for constant that this proposition : I am, I exist, necessary is true each time I pronounce it or conceive it in my mind” (Meditations on First Philosophy).

Thinking that Descartes could have been that naive or “so intellectually stupid” (cf. Thibault Gress) to deduct existence from a concept (i.e. to deduct existence from the thinking of existence), while Descartes himself denounces the sophism it would be, this is however what Kant will wrongly do (calling it  the ontologic argument or the ontologic proof) in his Critique of pure reason.7

2. A similar misunderstanding, quite widespread even nowadays, relates to what is known as Dualism (mind-body) or Bifurcationism (Northhead’s wording), i.e. the Descartes’ metaphysically determined principles: internal conscience and the external world, or the res cogitans (“thinking thing”) and the res extensa (“extended thing”). If these two principles were as heterogeneous as it may look, connecting mind and body (more precisely, explaining their reciprocal influences) would be the main problem of Cartesianism. Which is exactly what it has been; Cartesians like Malebranche, Spinoza and, to some extent, Leibniz, developed their respective solutions to solve (to save!) the irrefutable union of mind and body, respectively: Occasionalism per which God is cause of the concordance, Parallelism within a unique substance, Preestablished harmony. Yet, this union of mind and body never was an issue for Descartes. The thing is not a something, is not an entity, the only one entity is the individual (as etymology says: who cannot be divided): “I am intermingled with it, so that I and the body form a unit” (cfMeditations). To make it clear, for Descartes, there is at least one reality (one entity), which, in his very being, has nothing to do with bifurcationism : it is the man. The union of soul and body, is a substantial union. Not being at all a mix, this substance is our very being, underlying soul and body8.

Descartes’ vocabulary, specially once put out of context, may not be perfect or even adequate, but, as he specifies that mind is a substance, but that the body only consists of accidents, Dualism can be considered as some “invented Cartesianism”, which seems to be the state of current academic knowledge on this matter (cf. André Charrak). As example, we all know about his animal machine, but maybe not that, for Descartes, animals may well have a soul; but, whether or not they have one, the answer is just not required to deal scientifically with them (at that time).

Thus, in line with his initial Discourse on the Method, Descartes’ mechanism rather is a proposed method of knowing – and he is rightly credited to have initiated epistemology –, a method of science, be it what it was.

Some True Guilty Ones: Galileo, Kant.

If there is a need for determining, within the so complex history of thinking, who the true culprits would be, here some proposals.

If we want to condemn a purely “mathematical writing of the book of the Universe” (exempt of qualities) or an external world reduced to some “physical infinite empty space”9, Galileo is the best candidate. Here, for sure, we talk physics.

If we want to condemn the affirmation that there is no possible knowledge of external things, Kant is the best candidate. Admittedly, Descartes reduced the nature of the soul to the only dimension of thinking substance, forgetting about the various prior traditional souls (vegetative, sensitive, rational, intellectual). Now, the drama is that he compacted the two instances: reason and intelligence (while, as a metaphysician, he kept the possibility of intuition, though). This is where, certainly influenced by the apparent reduction, Kant removed the possibility of intuition, a tragedy! Yet, although these two faculties are one only—according to St. Thomas Aquinas—, reason is the act of discursive thinking, while intellect enables us to intuitively and inwardly fathom the truth. Reason is “the power of judging and distinguishing truth from error,” while to intelligence corresponds the faculty of understanding: intellection10. The disaster is that Western world was largely seduced by Kant reductionism, and so, metaphysics became theoretically impossible for a long while. Whitehead is one of those who refused to remain trapped into reason and, obviously, was right to refuse the bifurcation between what our perceptions convey to us from reality and what our thinking teaches us about it –bifurcation which is not (directly) from Descartes.

To conclude, we would like to say that the point was not to defend Descartes –as we can reproach him with many things like his materialistic physics or his compaction of intelligence and reason—but to reestablish, if ever necessary, the truth concerning his responsibilities in physics.

Was Newton a Newtonian?

The senseless ‘infinite empty space’, while definitely the one of Galileo, Henry More († 1687), Roger Cotes († 1716) and others, is not essentially Newtonian, contrary to the general opinion and, curiously, contrary to Newton pseudo-victory over Leibniz and Descartes.

Effectively, for the later: to the planet movements around the sun corresponds an harmonic circulation of a fluidic ‘ether’ (Leibniz), while for Descartes, it is due to large ether’s eddies filling up space and maintaining planets on their trajectories (for him, vacuum does not occur in nature, but it is filled with materia subtilis). Yet for Newton, attraction force was the proof of the shortcoming of pure and simple mechanics, a demonstration of existing superior forces, the manifestation of God’s presence and action in the universe. Now, after the dispute with the “etherists”, he had to adopt some ‘methodologic positivism’, to renounce any specific metaphysical or theological background, and to make attraction a purely natural force, a property of matter, so as mechanics was reinforced instead of being superseded. A Pyrrhic victory! (cf. Alexandre Koyré).

However, behind this methodologic or scientific reduction, Newton still believes that the gravitational force is transmitted through space via some ether, a sort of substance devoid of physical property and filling up space and bodies. As example, he would write: “until now, I have explained celestial phenomena & those of sea by the gravitation force, but I nowhere assigned the cause of this gravitation” (cf. Principia Mathematica). Moreover, Newton will try to give it a metaphysical and religious signification, defining absolute space as sensorium Dei, i. e. space is the modality per which God is universally present to all things; space is not a substance, some eternal and infinite being, but a property or a continuation of the existence of the infinite and eternal Being (cf. Jean Borella). Note: one must remember that, out of all manuscripts left by Newton, half concerns theology, one quarter alchemy and the rest only physics.

Anyway, if one wants to condemn the senseless ‘infinite empty space’, one must get on Galileo, rather than on Descartes or Newton. In the Galilean science, the mathematical treatment of the reality is supported by the ontological reduction of the universe down to the only dimension of space; here, the essence of corporeal substance is pure extent (while Descartes space, as mentioned, is not substantial). Nowadays, after Paul Dirac’s “sea” (vacuum as an infinite sea of negative energy particles) and Einstein rehabilitation of Descartes (“physical objects are not ‘in space’, but these objects have a spatial extent”11), so the concept of ‘empty space’ loses its meaning), quantum physics defines vacuum as the minimal energy state, where spontaneous and ephemeral materializations of particles & anti-particles take place (quantum fluctuation of “vacuum”).

On the other hand, to condemn space uniformity or the reduction of planets to a single ‘mass point’ located at its center, Newton is the perfect candidate, having signed the effective origin of it. However, the issue here is not the mathematical reduction of the reality—science is necessarily a reduction to selected object and tools—, but, once this superficial reduction is accomplished, to forget it was one and to induce a false metaphysics. Again, the reproach shall be to Galileo rather than to Newton –Galileo being the most catholic from the two of them12.

As a Conclusion

Aristotle was more aporetic than Aristotelians made him look like; as such Aristotle was not Aristotelician. St. Thomas Aquinas is very different to his portrait by the Neothomism; as such he was not Thomasian. Have we kicked down an open door? As we often get acquainted to specific authors via their continuators or commentators or detractors, as well as via our own Weltanschauung and intellectual capacities, we always run the risk of misinterpretations.

It may always be useful to remember it, as this is the case… in my case as well.


  1. His Philosophiæ Naturalis Principia Mathematica, stating the law of universal gravitation, is published on July 5th, 1687 (further editions in 1713 and 1726).[]
  2. Written in 1629-1633, it will be finally published after his death.[]
  3. The complete title is significant: Discourse on the Method of Rightly Conducting One’s Reason and of Seeking Truth in the Sciences (1637).[]
  4. Meditationes de prima philosophia (1641).[]
  5. Principia Philosophiæ (1644).[]
  6. In this respect, the fact that Descartes laws of motion are all wrong (except the first one) is not the point. The point was to demonstrate the necessity of these laws. Newton will later formulate them properly (1687).[]
  7. What has been wrongly called the ontological proof of God existence proceeds from a similar misreading of Descartes by Kant. Thinking of God is not thinking his existence, but it is because He is that one can think of Him. Descartes, with all his faults, unlike Kant, remains a true metaphysician and, going on alike the Cogito, far from some “I think of God, therefore He exist”, he realize that this is because God is, that I can think of Him”.[]
  8. See our Introduction to Jean Borella, Wolfgang Smith, Rediscovering the Integral Cosmos: Physics, Metaphysics, and Vertical Causality, Angelico Press, 2018.[]
  9. This is such Galileo’s physics that led to his (light) conviction, rather than his Two Chief World Systems.[]
  10. See our Metaphysics of the Christian Mystery, ch. 1 Intelligence and reason (Angelico Press, 2018), see also “Unmasking ‘AI’” (, 2018).[]
  11. Relativity – The Special and the General Theory (F. trad. R. Lawson, 1961), foreword to the 9th edition.[]
  12. Contrary to the general believes, Galileo could be quite dogmatic, as example when he wrote: “any proposition, taught but not demonstrated, must be judged undoubtfully false, as soon as it contain anything contrary to the Scriptures”! (Letter to Christine de Lorraine).[]