René Descartes

versione
italiana

a cura di
Jean-Paul De Lucca
University of Malta

René Descartes (1596-1650), is generally considered the father of modern philosophy for no philosopher before him had so convincingly and radically challenged the established edifice of knowledge and cultural heritage of the past while attempting to construct a new system of knowledge by seeking to give philosophical inquiry new foundations. 

Descartes was born in a small village called Le Haye (Touraine, France), which was later renamed Descartes in his honour. He was educated at the renowned Jesuit college of La Flèche, where he received a typical scholastic education, before moving to the University of Poitiers. After graduating in law he interrupted his university studies to be able to pursue a long voyage around Europe. He writes in the Discourse on Method (1637) that he intentionally left the university in order to be able to learn from the great book of nature. Adrien Baillet, one of Descartes’ early biographers, reports (in La vie de M. Descartes [1691]) an interesting detail of these voyages, which is very often overlooked. In the cold German winter of November 1619, while serving with the troops of Maximilian of Bavaria, Descartes spent the whole day closed in a room enjoying the heat of his stove. Here he had the opportunity to freely converse with himself about his own thoughts. This situation reminds us of the scene he describes in his most famous work, the Meditations (1641). 

Descartes was a very prudent person and discreetly kept away from public attention. When he completed one of his most important early works, The World, he stopped its planned publication because of the outcome of the notorious Galilean affair. In this work, Descartes defended the heliocentric theory of Copernicus and refuted the traditional Aristotelian thesis that the celestial world and the terrestrial world were completely different from each other. He did not publish his work for the simple reason that he wished to live a quiet life without any torments. Confiding with his friend Marsenne, Descartes remained nonetheless convinced of the validity of his arguments. 

Having accepted the invitation of Queen Christina of Sweden to act as her personal tutor, Descartes moved to Stockholm in September 1649. So as not to disregard her royal duties, the Queen ordered the philosopher to give her lessons at five o’clock in the morning. Since his childhood years, Descartes had the habit of waking up late in the morning because of health reasons. This sudden change, which was further aggravated by the extremely harsh Swedish winter, led to Descartes falling seriously ill with pneumonia, the cause of his untimely death on 11 February 1650, just a few months after reaching Queen Christina’s court. 

Descartes’ genius first became evident in the field of mathematics. He is credited as the inventor of the branch of mathematics that applies algebra to geometry, also known as co-ordinate geometry. He also invented the graph, and the points on it are still called the Cartesian co-ordinates. Descartes had held mathematics in very high esteem ever since his school days at La Flèche. In his reflections in the Discourse he admits that his formal education had left him with nothing substantial apart from mathematics. Descartes was amazed at the clarity and reliability of the certainties mathematics provided and it became his lifelong ambition to try and apply this method to other fields of knowledge. He observed that mathematical proof started with the most simple, basic and indubitable premise and moved logically to a further step which was equally simple. By the end of this deductive process, mathematics could explain the more intricate and unclear questions. Mathematics provided two important characteristics; clarity and distinctiveness. These characteristics left an indelible mark on the pursuit of knowledge in all fields, chief amongst which that of modern science. In place of the old and shaky foundations of knowledge, Descartes proposed totally new foundations based on mathematical truths that are clear and distinct. 

The next question Descartes posed to himself was how this method could be applied to non-mathematical knowledge. The basis had to the same: an indubitable premise. Descartes thought that traditional metaphysics took too many things for granted, stating supposed truths on the basis of very doubtful premises. This is where his hyperbolic doubt is introduced. We do find philosophers before Descartes suggesting doubt as a means of getting closer to the truth (e.g. Tommaso Campanella’s 14 dubitationes in the Metaphysica) but none of them before Descartes had established it as the method. Once a basic premise is found to be indubitable, then one could proceed logically to deductively reach clear and distinct conclusions. Descartes’ most renowned application of his method is to be found in the argumentation he presents in the Meditations (the full title of which was Meditations on First Philosophy in which the existence of God and the immortality of the soul are proven). Using his method of doubting everything (de omnibus dubitantium), including his own senses, Descartes establishes one indubitable truth, that he exists. Put very briefly, in the Meditations, he goes about presenting his argument in the following manner. While sitting in his armchair by the fire place, the first thing he doubted were his senses. He knew that his senses could deceive him because he was aware of the possibility of optical illusions and therefore he saw no reason why he should not doubt that his senses could deceive. Thus, Descartes cannot rely on his senses. He then thinks to himself that only a madman would doubt whether his arms or his legs really exited. His reply is immediate: what if he was dreaming? He had in the past dreamt of sitting on the armchair by the fire looking at his hands. Yet, he was not really seeing them. So the senses can definitely not be trusted and cannot be used as an indubitable foundation for further investigations. Descartes goes on to think that whether or not he is dreaming, however, mathematical truths are never false. Two and three always add up to five and a square always has four sides, he says. Applying the hyperbolic doubt once again, Descartes imagines that the creator of the universe is not the benevolent God of Christianity but a malicious demon whose constant aim is to deceive him. So even the most simple mathematical judgements could be false. Can one be sure that this demon does not exist, Descartes asks? The answer is no and so Descartes assumes that the whole of reality is indeed the dream of an evil demon. At this point Descartes asks himself whether there is anything that is indubitable and his answer is that one and only one thing that cannot be doubted and that is that he is thinking, and if he is thinking, he exists (cogito, ergo sum). This was necessarily true even if his senses were deceiving him, and if he was dreaming, and if an evil demon tried to deceive him. It could not be denied or doubted without self-contradiction (If I say “I doubt I exist” I am proving I exist!). It is important to note already at this stage that Descartes states that it is his consciousness (his mental activity, his cogito) he cannot doubt and not the existence of his body. This is the basis of his dualism. 

The cogito argument (in French: je pense donc je suis) – remains synonymous with Descartes’ name. The claim “I think, therefore I am” (the translation is perhaps rather inept) was, according to Descartes, the only indubitable truth. He used this as his basic premise to move on to logically prove the existence of God (which can be considered a new version of the old ontological argument) and the world around him. In synthesis, Descartes posits his arguments as follows. Descartes looks at the only thing that is indubitable, his own mind, and he finds there certain innate ideas (an essentially Platonic notion). These included the concepts of “self”, “God”, and “substance”. Descartes then went on proving the existence of God using an ontological argument (like St. Anselm this argument is posited a priori and makes no reference to external world since at this point Descartes could only rely on his mind at). Using a version of the ontological argument he “proved” the existence of God because, he says, the concept “God” (who is perfect, infinite etc.) cannot have originated in him and therefore it must have been God himself who imprinted the idea of Himself in his mind. Once God is proven to exist, the evil demon cannot be regarded as the creator of the universe and therefore Descartes could accept the truths of mathematical judgements (the demon was the only objection to this). If mathematics is accepted as giving clear and distinct truths (certainty), we can believe that the account of reality given through mathematical physics is correct (scientific investigations such as those of Galileo, therefore, were not incompatible with the Christian faith). Thus, through because he could rely on truths of physics, Descartes “proved” the existence of the external world.  

Descartes’ used skepticism (doubt) as a method to ultimately defeat skepticism itself because what is true is true because it is clear and distinct, indubitable. 

Another aspect of Descartes’ philosophy, which was almost immediately criticised by none other than the other great rationalist, Spinoza, is his dualism. Reminiscent of the Platonic conception of the distinction between the mind and the body, Descartes held that the mind was a purely thinking substance (res cogitans) whereas the body was a purely material substance (res extensa), a mere material extension in which the mind could function. This led to his mechanistic view of the body, to the extent that Descartes considers animals as mere machines. Notwithstanding Spinoza’s effective opposition to this doctrine, it nonetheless had an immensely powerful effect on Western philosophy right up to the twentieth century and still today a number of philosophers subscribe to some form of Cartesian dualism. Descartes’ argument can be summarised as follows: When posits the cogito argument, that he exist is beyond doubt but that his body exists is not an indubitable truth. So, he says, his existence is independent of his body and therefore he cannot be certain that he exists when he is not thinking. This means that our existence depends on our thinking. Therefore, we are, in essence, a thinking thing (res cogitans), or what we could call a mind or a soul. Our body is nothing more than a machine, extended matter (res extensa) which serves as a vehicle of our mind.  

The problem with this argument is that just because we are unable to doubt that we are thinking but can doubt that we have bodies does not prove that we exist separately from our bodies. Descartes seems to be implying that just because we can doubt something we should proceed on the assumption that it is false rather than uncertain. It is like saying that just because we can doubt that there is life on other planets (because we lack certainty) it is necessarily false – rather than uncertain – to say that there actually is life somewhere else in the universe. Descartes seems to be committing the mistake of using doubt as some kind of proof.  

Descartes’ radical division between the mind and the body led to the question on where these to things meet in the human person, who had both a mind and a body. Descartes’ answer, which radicalised his already radical dualism even further, was that in the human person the res cogitans and the res extensa meet in the pineal gland. Even if this were true, one could argue that by locating the res cogitans in the pineal gland, Descartes was defeating his own argument that the location was a mode of the res extensa (body) and not of thought. Descartes, however, did little to explicate further his dualist position, which was soon to be rejected by other great philosophers, even those who considered themselves as “Cartesians” or as “Rationalists”.