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In the science fiction movie The Matrix, Morpheus asks Neo a simple question: Will he take the blue pill or the red pill? If he takes the blue pill, he will go on with his life and forget that he ever met Morpheus. If he takes the red pill, he will learn what the world is really like. As Morpheus says, “All I am offering is the truth, nothing more.”
Neo takes the [Spoiler Alert!] red pill, forever changing his understanding of reality. As it turns out, the world is actually ruled by machines imbued with artificial intelligence. Neo’s actual body is connected to a vast power grid, and his mind has been connected, not to the real world, but to the simulated reality of the Matrix.
Now this is all pretty far-fetched. From chess-playing computers like Deep Blue to large language models like ChatGPT, computer scientists have made a lot of progress when it comes to artificial intelligence. But we are still far from a place where artificial intelligence could take over and trap us in an entirely simulated world.
At the same time, isn’t it possible that we are in the Matrix? That artificial intelligence has actually already been developed, and that it is now creating the illusion that we are just discovering it? What evidence do you have to rule this out?
In today’s reading, we will critically examine Descartes’ arguments that reality is not what it appears to be. Even though Descartes wasn’t thinking about the Matrix, he still made the case that we might all be dreaming, or that we might all be deceived by an evil demon. Is there any way that we can rule these things out?
René Descartes (1596-1650) was a French mathematician and philosopher and is considered the father of modern philosophy. Coinciding with a period of scientific exploration and discovery in Europe, modern philosophy emphasized the use of reason over a dependence on traditional ways of thinking about the world. Embodying this spirit, Descartes split with many of the medieval and scholastic philosophers that came before him and attempted to build a philosophical system from scratch. In his Meditations on First Philosophy, Descartes begins this project by considering how much we can know about the world around us.
Descartes splits his meditations up into six parts. In this first meditation, which will be the topic of this reading, he begins by considering which of our beliefs we should be certain about and which we have some reason to doubt. If you’re interested, the full text of all six of Descartes’ Meditations can be found here.
Cartesian Method of Doubt – A process employed by René Descartes of rejecting all beliefs that he had at least some reason to doubt in order to see if he had any beliefs that he could know with certainty
A Priori Knowledge – Knowledge that can be gained without having any particular concrete experiences. Such knowledge is typically gained by rational insight or intuition
A Posteriori Knowledge – Knowledge that can only be acquired through having particular, concrete experiences. Such knowledge can be gained simply through our everyday experiences, or through more complex means like controlled scientific experiments
Philosophical Skepticism – The position that we do not know many things that we ordinarily take ourselves to know
The Evil Demon Argument – Argues that we cannot hold any of our beliefs with certainty because we could be radically deceived by an evil demon. A classic argument given by Descartes for doubting the reliability of almost all of our beliefs
Descartes begins his investigation by explaining the project he is embarking on and laying out the method he will use to reach his conclusions.
Meditation 1, Paragraphs 1-2
Several years have now elapsed since I first became aware that I had accepted, even from my youth, many false opinions for true, and that consequently what I afterward based on such principles was highly doubtful; and from that time I was convinced of the necessity of undertaking once in my life to rid myself of all the opinions I had adopted, and of commencing anew the work of building from the foundation, if I desired to establish a firm and abiding superstructure in the sciences. But as this enterprise appeared to me to be one of great magnitude, I waited until I had attained an age so mature as to leave me no hope that at any stage of life more advanced I should be better able to execute my design.
But, to this end, it will not be necessary for me to show that the whole of [my former opinions] are false—a point, perhaps, which I shall never reach; but as even now my reason convinces me that I ought not the less carefully to withhold belief from what is not entirely certain and indubitable, than from what is manifestly false, it will be sufficient to justify the rejection of the whole if I shall find in each some ground for doubt. Nor for this purpose will it be necessary even to deal with each belief individually, which would be truly an endless labor; but, as the removal from below of the foundation necessarily involves the downfall of the whole edifice, I will at once approach the criticism of the principles on which all my former beliefs rested.
In this passage, Descartes explains that he wants to establish a firm foundation for the sciences. Descartes disagreed with many of the scientists that came before him, particularly in how they were inspired by certain Aristotelian philosophy, and so his project was to create a basis for science that was not vulnerable to such errors. In order to do this, Descartes employs the Cartesian Method of Doubt. Following this method, Descartes doubts all of his beliefs that there is a chance he could be wrong about, even if that chance seems very remote and far-fetched.
Check out this video to hear the Cartesian Method of Doubt explained by a philosophy professor:
Meditation 1, Paragraphs 3-4
All that I have, up to this moment, accepted as possessed of the highest truth and certainty, I received either from or through the senses. I observed, however, that these sometimes misled us; and it is the part of prudence not to place absolute confidence in that by which we have even once been deceived.
But it may be said, perhaps, that, although the senses occasionally mislead us respecting minute objects, and such as are so far removed from us as to be beyond the reach of close observation, there are yet many other of their informations (presentations), of the truth of which it is manifestly impossible to doubt; as for example, that I am in this place, seated by the fire, clothed in a winter dressing gown, that I hold in my hands this piece of paper, with other intimations of the same nature. But how could I deny that I possess these hands and this body, and withal escape being classed with persons in a state of insanity, whose brains are so disordered and clouded by dark bilious vapors as to cause them pertinaciously to assert that they are monarchs when they are in the greatest poverty; or clothed [in gold] and purple when destitute of any covering; or that their head is made of clay, their body of glass, or that they are gourds? I should certainly be not less insane than they, were I to regulate my procedure according to examples so extravagant.
At first, Descartes finds it almost unthinkable that he could doubt his senses. But then he considers the possibility that what he is experiencing isn’t actually produced by his senses at all, but is rather part of some elaborate dream. If this is true, he might not be able to trust his experiences after all…
Meditation 1, Paragraph 5
Though this be true, I must nevertheless here consider that I am a man, and that, consequently, I am in the habit of sleeping, and representing to myself in dreams those same things, or even sometimes others less probable, which the insane think are presented to them in their waking moments. How often have I dreamt that I was in these familiar circumstances, that I was dressed, and occupied this place by the fire, when I was lying undressed in bed? At the present moment, however, I certainly look upon this paper with eyes wide awake; the head which I now move is not asleep; I extend this hand consciously and with express purpose, and I perceive it; the occurrences in sleep are not so distinct as all this. But I cannot forget that, at other times I have been deceived in sleep by similar illusions; and, attentively considering those cases, I perceive so clearly that there exist no certain marks by which the state of waking can ever be distinguished from sleep, that I feel greatly astonished; and in amazement I almost persuade myself that I am now dreaming.
If Descartes is right and we can’t distinguish when we are dreaming from when we are awake, what does this mean for our sensory experiences? Should we doubt everything that we learn from our senses? Another issue is how these reflections apply to different areas of study, subjects like physics, arithmetic, and geometry. Can we trust what we learn about these subject matters?
Meditation 1, Paragraphs 6, 8
Let us suppose, then, that we are dreaming, and that all these particulars—namely, the opening of the eyes, the motion of the head, the forth-putting of the hands—are merely illusions; and even that we really possess neither an entire body nor hands such as we see. Nevertheless it must be admitted at least that the objects which appear to us in sleep are, as it were, painted representations which could not have been formed unless in the likeness of realities; and, therefore, that those general objects, at all events, namely, eyes, a head, hands, and an entire body, are not simply imaginary, but really existent. For, in truth, painters themselves, even when they study to represent sirens and satyrs by forms the most fantastic and extraordinary, cannot bestow upon them natures absolutely new, but can only make a certain medley of the members of different animals; or if they chance to imagine something so novel that nothing at all similar has ever been seen before, and such as is, therefore, purely fictitious and absolutely false, it is at least certain that the colors of which this is composed are real. And on the same principle, although these general objects, viz. [a body], eyes, a head, hands, and the like, be imaginary, we are nevertheless absolutely necessitated to admit the reality at least of some other objects still more simple and universal than these, of which, just as of certain real colors, all those images of things, whether true and real, or false and fantastic, that are found in our consciousness, are formed.
We will not, therefore, perhaps reason illegitimately if we conclude from this that Physics, Astronomy, Medicine, and all the other sciences that have for their end the consideration of composite objects, are indeed of a doubtful character; but that Arithmetic, Geometry, and the other sciences of the same class, which regard merely the simplest and most general objects, and scarcely inquire whether or not these are really existent, contain somewhat that is certain and indubitable: for whether I am awake or dreaming, it remains true that two and three make five, and that a square has but four sides; nor does it seem possible that truths so apparent can ever fall under a suspicion of falsity [or incertitude].
Even though Descartes concludes that he cannot trust his senses, that doesn’t mean that we have to throw out everything we believe about the world. In particular, he thinks that we can hold onto our a priori knowledge. A Priori Knowledge can be learned just by thinking. Consider Descartes’ example that 2+3=5. This isn’t something we can only learn by experiencing the world. If I know that I have a carton of 2 apples on the counter and 3 in the refrigerator, I do not need to check and see whether I have 5 apples. I know that 2+3 is always equal to 5, and so Descartes thinks that I do not need to doubt that this is true even when I am dreaming and deceived about my sensory experiences. Among the subjects that can be learned a priori, Descartes includes arithmetic and geometry.
A Posteriori Knowledge, on the other hand, is vulnerable to misleading dreams. A posteriori knowledge can only be gained by learning about the real world, and so if our senses lead us astray, this can prevent us from learning what the world is like. Some examples of things that have been discovered a posteriori include the strength of gravity or that water boils at 100° Celsius. These are not truths that we can arrive at only by thinking, and we only learned about them through scientific discoveries about the way the world works. If we’re dreaming though, all bets are off!
So far, Descartes has entertained a form of Philosophical Skepticism, doubting that he knows many things which we ordinarily take ourselves to know. But philosophical skepticism can come in stronger or weaker forms. Descartes started out by doubting some of the things which he learned via his senses, and then used the dreaming argument to doubt that he knows anything except certain a priori propositions. In this passage, we’ll see that Descartes thinks that there is reason to doubt even 2+3=5 right alongside scientific claims like water boiling at 100° Celsius.
Meditation 1, Paragraphs 9, 12
Nevertheless, the belief that there is a God who is all powerful, and who created me, such as I am, has, for a long time, obtained steady possession of my mind. How, then, do I know that he has not arranged that there should be neither earth, nor sky, nor any extended thing, nor figure, nor magnitude, nor place, providing at the same time, however, for [the rise in me of the perceptions of all these objects, and] the persuasion that these do not exist otherwise than as I perceive them? And further, as I sometimes think that others are in error respecting matters of which they believe themselves to possess a perfect knowledge, how do I know that I am not also deceived each time I add together two and three, or number the sides of a square, or form some judgment still more simple, if more simple indeed can be imagined? But perhaps Deity has not been willing that I should be thus deceived, for he is said to be supremely good.
I will suppose, then, not that Deity, who is sovereignly good and the fountain of truth, but that some malignant demon, who is at once exceedingly potent and deceitful, has employed all his artifice to deceive me; I will suppose that the sky, the air, the earth, colors, figures, sounds, and all external things, are nothing better than the illusions of dreams, by means of which this being has laid snares for my credulity; I will consider myself as without hands, eyes, flesh, blood, or any of the senses, and as falsely believing that I am possessed of these; I will continue resolutely fixed in this belief, and if indeed by this means it be not in my power to arrive at the knowledge of truth, I shall at least do what is in my power, viz., [suspend my judgment], and guard with settled purpose against giving my assent to what is false, and being imposed upon by this deceiver, whatever be his power and artifice. But this undertaking is arduous, and a certain indolence insensibly leads me back to my ordinary course of life; and just as the captive, who, perchance, was enjoying in his dreams an imaginary liberty, when he begins to suspect that it is but a vision, dreads awakening, and conspires with the agreeable illusions that the deception may be prolonged; so I, of my own accord, fall back into the train of my former beliefs, and fear to arouse myself from my slumber, lest the time of laborious wakefulness that would succeed this quiet rest, in place of bringing any light of day, should prove inadequate to dispel the darkness that will arise from the difficulties that have now been raised.
In this passage, Descartes imagines a demon powerful enough to deceive him about everything he believes (there is actually one key belief that he thinks he can be certain about, but we’ll have to save that for his second Meditation!), giving him at least a small reason to doubt all that he thinks is true. If we lay out The Evil Demon Argument using premises and a conclusion, it would look something like this:
Premise 1: It is possible that I could be deceived by a powerful demon about everything I believe
Premise 2: If it is possible that I could be deceived by a powerful demon about everything I believe, then I cannot be certain about anything that I believe
Conclusion: I cannot be certain about anything that I believe
Descartes motivates the first premise by imagining a demon so powerful that it could deceive him at will, creating vast and complex illusions. In this case, the demon might even be capable of deceiving him about basic arithmetic, so strong would the illusions be. But, as we see with the connection drawn by the second premise, if such a demon does exist, then we cannot be certain about anything that we believe. While it might only provide us with a very small reason to doubt that the reality is as we take it to be, that can still provide us with a small reason for not being absolutely certain.
In Descartes’ First Meditation, we saw that he wanted to establish a certain foundation for his beliefs. In order to do that, he rejected all beliefs that he had at least some reason to doubt. By considering the possibility that he might be dreaming, he came to think that his senses could not be fully trusted, and the possibility of deception by a very powerful evil demon gave him reason to think that even things he thought he knew a priori, like his mathematical beliefs, could be mistaken. In his Second Meditation, Descartes picks up where we left off, considering whether he has any certain beliefs.
Are there any other arguments that can give us reason to doubt everything we believe? In our Warm-Up, we considered a world like the one depicted in the Matrix, where the experiences of most people are of a very sophisticated virtual simulation. If we think that this is a possibility that we can’t rule out, then we could create our own version of Descartes’ argument, starting with the premise that it is possible we are being deceived by very sophisticated artificial intelligence.
In fact, many contemporary philosophers use a different thought experiment than Descartes’ Evil Demon. In its place, they discuss whether we can know that we are not a brain in a vat. The example is discussed so often in philosophy, that there is now even an entire book focused on the thought experiment titled The Brain in a Vat! In many cases where this example is used, the imagined brain is kept alive and hooked up to a simulation by a mad scientist, but it could just as easily be controlled by advanced AI, just like we find in the Matrix.
If you’re curious where Descartes’ method of doubt ultimately takes him, pick up the story with his Second Meditation, where he lands on a conclusion of which he can be certain. And for an overview of how contemporary philosophers think about skepticism, see the articles “Contemporary Skepticism” and “The Brain in a Vat Argument” on the Internet Encyclopedia of Philosophy.
This work has been adapted from Meditations on First Philosophy, a title from the eCampusOntario Public Domain Core Collection. This work is in the Public Domain. All images were created using Midjourney and are the property of the Philosophy Teaching Library.
Siscoe, Robert Weston. 2023. “Doubt Everything: Rene Descartes’ Meditations on First Philosophy, Meditation 1.” The Philosophy Teaching Library. Edited by Robert Weston Siscoe, <https://philolibrary.crc.nd.edu/article/doubt-everything/>.
