Intro Philosophy 9: Descartes & Hume
RENE DESCARTES (1596-1650) is considered the first modern European philosopher. He is known for the first canonical modern European philosophy texts, his Discourse on Method and Meditations, and also for the Cartesian coordinate system (X and Y as two dimensions), a device useful for algebra and critical for the later European development of calculus by Newton and another early modern European philosopher acquainted with Descartes’ thought, Leibniz. While Newton is far more famous as a scientist, we use Leibniz’s mathematical notation system in calculus because Newton named everything after himself, creating a system that was not only vain but needlessly confusing.
Descartes’ philosophical writings, particularly the Meditations, drew the reactions of several philosophers who themselves went on to become famous, particularly Spinoza, Hobbes, Hume, Leibniz, and Locke. In this class, we cover Hume. If you would like notes on the others in this list, please check out the notes on them under Modern European Philosophy.
In the Meditations, of which I gave you central selections, Descartes asks: What we can know for certain if it is possible that everything is an illusion of the mind? Much like Avicenna did over five hundred years earlier, Descartes concludes that we can be certain that we are aware and conscious, famously writing, “I think, therefore I am“. From this, he proceeds to conclude that we can be certain that our thoughts are our own, that the world is real, that there are regularities in the world that we can know for certain, and that there is a good and loving monotheistic god who would not deceive us about these things.
Some philosophers agreed with this very much, but did not find Descartes’ argument convincing and tried to come up with more satisfying proofs. Other philosophers who were more skeptical, such as Hume, did not buy it and argued that human truth and certainty is always, in some way, an assumption. The two sides of the debate were known as Rationalism and Empiricism.
Rationalists like Descartes, such as Leibniz, believe that facts and certainties can be acquired by deduction from other facts and certainties, much like Descartes proceeds from awareness to a world with consistent, knowable and deducible facts. Empiricists, like Hume, believe that all human conceptions are acquired by induction, gathered perceptions of regularities and patterns, and that while deduction and certainty are useful it is always possible for them to be wrong.
Both sides agree that the world is quite regular in many ways, and that science should continue to examine and learn from the world, however the two see the success of science in opposite ways. Rationalists see science as proof that humans can acquire certain and true knowledge, while Empiricists see science as proof that humans can never be absolutely certain of their theories, conceptions, and understandings, but must be open to new experiences and information contradicting what was previously deduced as certain. Recall that in Islamic thought, one of the major debates was about which of the three types of reason (analogy, induction and deduction) is the highest and most primary. In the first major split in modern European thought, the Rationalists, like Descartes, go with deduction, while the Empiricists, like Hume, go with induction.
Descartes was born in Touraine, France, a town which has since been renamed ‘Descartes’ after its most famous citizen, and a statue of him has been placed in the town square. Descartes’ father was a member of parliament, though his mother died when he was very young. He went to law school to follow his father and become a merchant, but decided to become a mercenary instead travel and fight in the 30 years war, ‘to seek truth’. It seems he did not find truth in law school. As a soldier, he had much time waiting for battle, and studied mathematics and science in his spare time. On the night of November 10th, 1619, Descartes had a series of visions that convinced him that the world is a rational and mechanical system profoundly in tune with the rationality of the human mind.
At first, he intended on writing books on physics, but in 1633 Galileo was condemned by the Church for his solar-centric theory, the idea that the earth moves around the sun, which India and Islam had for more than 700 years. Interestingly, many put the sun at the center of the universe, replacing the earth as center. Because of Galileo’s troubles, Descartes decided not to publish his views on physics, his Treatise on the World, but his Discourse on Method, his philosophy text, instead, and it is today considered the first work of modern European philosophy. This caution did not spare Descartes however, as the work was condemned by the Pope in 1663, thirty years after Galileo’s work was condemned and after Descartes’ death, put on the prohibited index of books alongside other authors who are foundational for European scholarship. Like Aquinas, even though Descartes argued that reason teaches us that the Catholic Church is the one true religion and there is a monotheistic god, his heresy was teaching that it is reason that shows us this, not faith or the will of the heavens. Descartes remained a practicing Catholic until his death.
Descartes’ death is famous and unfortunately funny. For the majority of his life, he worked in bed until noon each day, an aristocrat who had the time and leisure to do this. After he became famous and his works were prohibited by the Catholic Church, the Protestant Queen Christina of Sweden invited him to Stockholm to be her private tutor. Unfortunately for Descartes, she wanted morning lessons, every morning, at 5 am. Between the snow and the early mornings, Descartes was soon sick with pneumonia, and died. Maybe we should all work on our problems every day until noon, safe in bed. This is similar to Francis Bacon’s famous death, catching pneumonia after repeatedly stuffing snow into chickens to try to preserve the meat and keep it from rotting. Some have argued that Descartes was killed with a poisoned communion wafer given by a priest who feared Descartes’ rationalism, but this is questionable as it sounds like a story Protestants in Sweden would invent to slander Catholics.
Last lecture, Islamic algebra and mechanics showed us the development toward modern society and thought. Descartes, in a world of increasing algebra and mechanics, turns from an understanding of causes up in the heavens to cause as the mechanics of this world. Just like many Islamic and medieval European thinkers, Descartes identifies the mind and heavens with freedom and consciousness while putting the mathematical order of things down in the world. The heavens remain the good and pure, but the order and mathematics becomes a thing of this world and not the other world. This change comes with a world increasingly full of algebra and mechanics. The world we see is the articulated, mechanical known, and the spiritual is the beyond and unknown. This goes in hand with the soul/mind ceasing to be round and made of fire and the heavens and afterlife ceasing to be physically above our heads even for the committed religious. While Descartes argued that a monotheistic god clearly created the world, as reason tells us all things have causes, he was condemned like Hobbes, Newton and others for arguing that nature works like a machine, and once caused proceeds largely on its own.
An excellent illustration of the world becoming mechanical and life as the unknown ‘ghost in the shell’ is the City of Brass story from the 1001 Nights, also called the Arabian nights. In the story, an exploration party of the Sultan sets off to discover King Solomon’s lost City of Brass, a place where he kept demons in brass bottles, forced them to forge many wonderful pieces of metalwork in furnaces and used mysterious forces from below to produce technological wonders in this world, a thing that he can do only because he is very holy and wise. In the story, there are many evil robots that still kill long after Solomon is dead and gone. This comes from the Islamic tales of Solomon, that say when he died he stayed upright for a century and the demons continued to work on their tasks not knowing that their master was dead. Then a worm ate through Solomon’s staff and he fell over, and the demons realized that they had been working for no purpose and fled.
In the City of Brass, a beautiful extension of the story, there are beautiful marionettes that move and beckon in the wind, luring some of the exploration party to their deaths in gorges below. There are other sorts of dangerous automata that are empty bodies still moving from natural forces. Finally, Solomon’s Queen (not Sheba who went to Ethiopia, but another) is stuffed and preserved, sitting on her thrown, with her eyes mechanically blinking every so often. One of the party falls in love, approaches, and only realizes when touching her hand that she is dead, and he reels back in horror. Think of this as a medieval Islamic science fiction story, similar to killer robots and zombie flash mobs of today.
Descartes now proceeds to make the natural world, including animals, nothing but mechanics and causation, completely devoid of intention or feelings. Dualism is the position that mind and body are two separate things. Spinoza, against Descartes, argued for monism, that there is no difference between the body and mind, between the physical world and the spiritual, for which he was attacked and condemned. Descartes argued for a radical dualism between the mechanics of the world below (body) and the consciousness and intention of the world above (mind). Consciousness or mind or spirit is in the upper world, while all in the given world is mindless mechanics. The worst of this is that Descartes practiced vivisection, cutting animals apart while alive to learn about anatomy, and helped popularize the practice in Europe, arguing that animals do not have minds and thus do not feel a thing, their behavior being mere automatic reflexes of causal forces.
This same cultural current is what led Protestantism to lose saints and angels with functional roles and simply pray directly to Jesus for everything, different from all previous world religious systems (including Catholicism). In early Europe, Jesus was busy battling the dragon Satan. If your cow got sick, there was a specific saint or angel to petition. Asking Jesus for small favors is like calling the president about a stop sign in your neighborhood. With increasingly sophisticated practices of medicine and then veterinarian practice, you no longer take your sick cow to a particular temple and pray to a particular saint as a particular priest uses medicine as well as prayer and ritual to heal your cow. The causal solution is now one of this world, but the ‘evil’ of sickness remains distantly rumbling in the world beyond, not gone but no longer the primary force of the institutional practice. Temples become increasingly research facilities, science and religion specialize and part ways.
Let us remember Avicenna’s floating man thought experiment. In what some call the first ‘thought experiment’ (the central device of the American tradition of philosophy), he suggests that the reader imagine floating in a void and having all sensation, including of the body or senses, slowly taken away. What are you left with as the essential factor once the accidental sensual factors are removed? Self consciousness, with the awareness of consciousness and mind itself. For Avicenna, as for Descartes, this awareness and self-circling is the small piece of God, the big all awareness, that is one’s soul, humanity and life.
Descartes proposes a very similar thought experiment. He asks the reader to imagine that there is a deceiving demon that is creating an illusion of the world, casting doubt on everything except the essence of the human being and soul, the self-awareness which Descartes believes proves that you must exist. Thus, his famous line: “I think, therefore I am”, a conclusion that has been violently debated back and forth ever since. One’s position is defined, in a sense, by what one thinks of Descartes’ simple experiment.
Where does the deceiving demon in Descartes come from? Why the radical psychological skepticism, and then the simple positive (skeptics would say ‘naive’) affirmation of existence? To see this, we must speak of the Cathars, a Gnostic Christian and Manichean hybrid Heresy that was being persecuted in France in the 1400s. Descartes is writing in France in the late 1600s, two hundred years later. Gnosticism spoke of a deceiving demon false god, the devil, that controls the appearance of this false world below, similar to the Indian doctrine of the world below as not only evil but illusion and false.
Manichaeism was a religion started by a Syrian named Mani (200-276 CE), who claimed to be the final coming of Jesus, the Jewish messiah, the third Saoshyant, the Persian Zoroastrian messiah, and the Buddha Amitaba, Buddha of Infinite light who will ferry people to the pure land. This is because Buddhism and Christianity flourished in Syria and Afghanistan as a middle ground of cultures. Then the religion was fused with much Zoroastrian terminology to become what Christians in Europe considered a Christian Heresy. The religion spread up through Europe in 300-500, and the Cathars were an offshoot that survived in France up until the persecutions of 1400s.
Thus, Descartes (the first modern philosopher) is arguing for Christianity and its simple positive faith in the world vs. the Cathar/Manichean/Gnostic deceiving demon. Descartes thought experiment is very much Avicenna’s floating man thought experiment, but notice that it also attacks the idea of the Cathar Satan or King Demon. Notice that Descartes’ thought experiment suggests that a Demon could not keep us in the dark the way the Cathars believe. Instead, because of our self-consciousness/mind/soul that we get from God, and then using this as an anchor of certainty, Descartes argues that God thus does not completely deceive us in this world but shows us many other certainties that we can know with the power and sight of our mind.
In his Discourse on Method, he lays out the famous “I think therefore I am” thought experiment, remarkably similar to Avicenna’s Floating Man thought experiment. He says he won’t tell us about his first meditations in hardcore skeptical ‘all is a dream’ mode, “for they are so abstract and unusual that they will probably not be to the taste of everyone”. Wow, keep that to yourself, Descartes. He starts with the meditations he will tell us about with a thought experiment: assume that all the senses are being tricked, as if by a dream. This is similar to Zhuangzi’s Butterfly, and now he doesn’t know what it is- but Descartes ends like Avicenna’s floating man. Everything can be doubted but the self-awareness. He writes that ‘I think therefore I am’ is the first principle of his new philosophy, brought up from the ground of this principle out of total skepticism of certainties. A skeptic here would wonder if this is so skeptical. First, Descartes assumes from self-awareness that he is a mind, a ‘substance of thought’, which is completely distinct from the body, which can be doubted. Already there are grey areas here. Can’t thought be doubted as much as a body part? Aren’t both ‘sensed’?
In his Meditations, lays the argument out step by step. We all accept things that we believe to be certain, but then turn out to be wrong. Therefore, we cannot use certainty as the sole criterion for truth. We have to separate out the categorically certain from the seemingly certain. Descartes says that it seems certain that he is sitting by the fire writing, but we can doubt this and believe that Descartes is simply dreaming that he is Descartes, by the fire. He uses the example of madmen who think that they are kings or that their bodies are made out of glass. Obviously, Descartes had some familiarity with at least literature about types of madness and delusions (also very Avicenna-like, who understood imagination and mental conditions such as hysteria and hallucinations).
There seem to be certain truths that cannot be untrue, like 2 + 3 is equal to 5, a central example he uses, or a square always has 4 sides. Notice that both of these are mathematical examples. However, we can even imagine that this itself is all delusion. Hence, we assume for skepticism’s sake that there could be a deceiving demon (much like in the movie The Matrix). He also says it could be someone extremely powerful who could use ‘industry’ to deceive me: this is the ‘brain in a vat’ mad scientist thought experiment used today rather than a demon in philosophy classrooms. The demon cannot convince me that I do not exist, and so I am an existent thing that thinks. The one point of certainty is self-awareness or consciousness, the one thing that we cannot be fooled about because it is self-evident. Descartes argues that the mind has no quality and no quantity, no space or time to it at all.
Hence, it is the human immortal soul/mind/awareness. Because we are sure of this, and because we get our truth from something that we are within we are not in the power of something that completely lies to us. Descartes then quickly declares that we can trust that God is good, the world is not an illusion and 2 + 3 is equal to 5. When we aspire to God and truth, using reason correctly, we discover certain truths, such as the truths of mathematics, the existence of the soul, and of God, the certainty that the body is not our true self, and that animals do not have souls or awareness. Note that everyone after Descartes found this reasoning a bit too quick and slim, both those who agreed with him and those who did not.
Finally, a quick joke I found on Reddit:
A horse walks into a bar and orders a beer. The bartender says, “You’re in here every day. You might be an alcoholic”. The horse says, “I don’t think I am,” and disappears. It’s a joke about Descartes, but you don’t want to put him before the horse.
DAVID HUME (1711-1776) did not agree with Descartes on much. Hume’s position is that all of our thinking, our identity and truth is induction and assumption. This is like the Indian theory of skandas, ‘piles’ of sand, speaking of the mind and how all perceptions in it are just bundles of stuff that accumulate and then dissipate. Interestingly also like Indian thought, particularly Buddhism, Hume argued that human thought, identity and behavior are ruled by the passions, not reason which serves as a tool for desires. With Locke and Berkeley, the Berkeley for which the town and university get their name, Hume is one of the three British Empiricists.
Hume was born in Edinburgh, Scotland. His name was originally spelled ‘Home’, but Hume changed it because the British and others kept mispronouncing it. Like Descartes, he originally planned to study law but came to a fascination with philosophy and devoted himself to it instead. During his lifetime his works on philosophy were condemned both by professors as unintelligible and priests as atheist, but his six volume History of England gained fame and was printed numerous times. While Hume was called an atheist by friends and foes, he was critical of religion but silent about his own beliefs. It is likely he was an agnostic, as he argued in various places that reason could neither prove nor disprove the religious beliefs of the world’s cultures. Like Nietzsche, whom Hume influenced in matters of desire as user of reason, Hume saw religion not as objectively true or false but as useful to a culture in a time and place, and in his History of England he argues that humans are creatures of habit who are often only moved to political revolution over matters of religion.
Hume’s An Abstract of A Treatise of Human Nature is the condensed form of Hume’s first and foremost work which he wrote after critics claimed his original Treatise of Human Nature was convoluted and difficult to understand. Hume starts saying that philosophy has flowered all over Europe in “these last four score years” (80 years, no connection to Lincoln or Gettysburg), and that it has occurred in England just as greatly as any other. Notice that philosophy is a recent development for Europe, as well as England. Hume says that philosophers of ancient times have handled their truths delicately, showing more restraint than full depth of reflection. Remember with Descartes, skepticism and critical reflection can quickly turn to orthodoxy. Hume is ultimately going to say that all truth is assumption, habit, and prejudice, which opens the gates on any accepted truth as needing to be continuously justified rather than simply proved, as well as opens up potential attacks on all established forms of truth.
Hume says that all mental activity are perceptions. Perceptions are divided into two kinds: impressions and ideas. Impressions are perceptions of objects that are present, and ideas are perceptions of objects that are not present or not directly perceived. For example, one has the perception of a red billiard ball on the table. If one turns around and doesn’t look at the ball, one has an idea of the ball and its appearance in one’s head. Likewise, if one looks at the still red ball and imagines it is moving, one has an impression of the ball and has an idea of the ball rolling down the table.
Likewise, if one looks at a moving red ball and imagines it is going to continue moving or hit another ball, one has many impressions of the ball as it moves that one gathers together with an idea of its continued future movement. Impressions are strong, while ideas are weaker. Hume argues that we derive all of our ideas from our impressions. Hume acknowledges that this is in line with Locke’s Tabula Rasa (Blank Slate in Latin). It goes directly against Descartes and Kant, who believe we can with the operation of reason, independent of experience, determine several truths that are correctly understood to be certain regardless of experience.
Hume presents us with his famous and central billiard ball analogy. Imagine two billiard balls, one red and one blue. There are three events. First, the red ball moves up to the blue ball. Second, there is the sound of a ‘clack’. Third, the blue ball moves away from the red ball. Naturally, and this is the key word here as we are talking about the habit, we all understand that the red ball struck the blue ball. Notice that we did not see or perceive the conjunction of the two events. We did not perceive the causation. The causation is itself invisible. Then how did we all understand it?
The answer is we have all shared common experience, and so we share ideas and prejudices. We all had an idea or prejudice when we watched the red ball moving toward the blue ball. Our impressions of things knocking into each other, and in particular our impressions of billiard balls and their motions, naturally caused us all to get into the habit of having a preconception, a preconceived idea, that the red ball was going to hit the blue ball and then the blue ball was going to move afterward. Then, when things happened as they usually seem to, we come to the conclusion either individually or as a group that we were right in our preconceptions.
Hume believes that this is all one can strictly say about the events, and that saying anything else, like suspecting that a particular ‘causation’ was there as an invisible presence, may be common idea that we share but it is not in fact directly perceived or known. It is an idea, not an impression, a concept and not a perceived object. Most often, our conclusions are correct, but whenever they are wrong, it shows us that we can have certainty and preconceived ideas, but these do not guarantee that we will be correct. For example, if we made a movie of the two billiard balls, it is an illusion that one image is striking the other. Obviously, we want the audience of the film to have this idea, but this does not make it any less of an illusion, whether the balls are filmed or animated.
In a sense, when we watch animation we know and don’t know that what is going on is ‘real’. We can ‘suspend’ our disbelief, and allow our minds to watch and believe in the animated events, even though any animated even must by its nature be fake caricatures of events. Likewise, we can construct an animatronic billiard table, like at a ride in Disneyland, that looks like objects are hitting each other over and over again even if the sound is artificial and the objects never touch. Roland Barthes, the French philosopher and literary critic, said that now that we have built Disneyland, maybe we will be more critical of the nonsense of politics.
Hume argues that all of our beliefs and truths are inferences that we draw, not certainties that we can know without qualification. This is true of life, history, and all of philosophy. If this seems hopeless in its skepticism, it is not entirely bad. Remember that most of our preconceptions are quite in accord with how things go, otherwise we would have no reason for forming them in the first place. While nothing can be known for certain, it is giving a different view of meaning. Things accumulate and build up in our ideas, and thus they are real to us. They are not so real that they ensure that nothing could ever contradict them, but they are real to us and we use them in the world.
Hume uses the example of Adam in the garden of Eden as a human who learns the motions of things by experience, starting with a blank slate. Hume says that even Adam, “with all his science, would never have been able to demonstrate that the course of nature must continue uniformly the same, and that the future must be conformable to the past.”
We are determined by custom alone to suppose the future conformable to the past. When I see a billiard ball moving towards another, my mind is immediately carried by habit to the usual effect, and anticipates my sight by conceiving the second ball in motion…It is not, therefore, reason which is the guide of life, but custom. That alone determines the mind, in all instances, to suppose the future conformable to the past. However easy this step may seem, reason would never, to all eternity, be able to make it.
With regard to any matter of fact, however strong the proof may be from experience, I can always conceive the contrary, though I cannot always believe it…Philosophy would render us entirely skeptical (Pyrrhoian) were not nature too strong for it.
Hume argues that effect is often variable and uncertain in life. As an example, he argues that thirty grains of opium will kill anyone that is not accustomed to it. Hume goes on to question the Cartesians’ (followers of Descartes) idea of a supreme being which is wholly without deception, the eternal self, and geometric/mathematical truths (2 + 3 = 5). He argues: how can they know this from experience? Our idea of God is a composition of our experience (guy with a beard, in the clouds) that we have not experienced directly so much as in other things. Mathematical and geometric proofs look nice, but sometimes geometry seems like it is proving something that later is disproved. This is similar to Xenophanes, who argued that horses and oxen would fashion the gods in their own image.
Hume argued that emotion and reason are always intertwined, just as experience and reason are always intertwined. He famously wrote, “Reason is, and ought only to be the slave of the passions”. Without desire, we do not reason. Recent literature about antidepressants suggests that when people are significantly devoid of desire, they do not find themselves thinking much, are not motivated to have significant ideas about important things. When we think much about something, we are passionate.
Hume argues that the great subverter of skepticism is employment, the occupations of common life. Because we must act and eat, we cannot afford to be entirely skeptical. While it is easier to be skeptical in a school or in the shade, as soon as we are passionate about things in the world skepticism, even for the hardened and determined skeptic, vanishes like smoke. The only genuine profession for the skeptic is philosophy. If the entire world were made of nothing but skeptical philosophers, humanity would die out, but thankfully we are naturally ignorant, passionate, and dogmatic, and so skepticism is continuously useful for showing most people the continuous errors of their ways and that for every position there is a counter position even if it does not seem apparent at first. Thus, while skepticism, philosophy and doubt would be worthless if they eclipsed all dogmatism, vocation and belief, they are the most useful of positions and vocations, in critical opposition to everything else on Earth.