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Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldDescartes: Meditations on First PhilosophyMarch 11–14, 2014Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldOverview IReviewMethodMethodological doubtDoubting the sensesDream-doubtThe demonFrom thereGod’s existencePreliminariesThe argumentFormal and objective realityP1P2P4RecapDescartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldOverview IIMethodological PrinciplePhysical worldDescartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldEpistemology: OverviewEpistemology theory of knowledge.1What is knowledge?Plato: Knowledge is justified true beliefGettier: Knowledge is NOT justified true belief2Can we know anything?Descartes: skeptical arguments: sense deception, dreams,demonPutnam: Brains in a vat3What is scientific knowledge?Aristotle: demonstrated, necessary, universalHume: problems with demonstration and universalityHempel: some more problems with demonstration anduniversalityDescartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldRené Descartes (1596–1650)French philosopher,mathematician, physicist“The first modernphilosopher”Mathematics: analyticgeometry; optics; mechanicsStudied at La Flèche (Jesuitcollege); degree in law.Met with some leadingscientists of his age (e.g.,Beeckman); interest innatural science.Lived in Holland in his laterlife.Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldThe MeditationsPublished in 1641Main aim: to provide a philosophical foundation for the newsciences (“the book of nature is written in mathematics”):Justification of the new scientific methodsEstablishing the certainty of the new sciencesFoundationalismThe view according to which everything we know can be built upfrom some infallible groundwork. The aim of the foundationalist:1to find this groundwork;2to show how everything else can be built up from there.“I realized that once in my life I had to raze everything to theground and begin again from the original foundations, if I wantedto establish anything firm and lasting in the sciences.” (p.9)Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldMethodological Doubt:Skeptical concerns are used to arrive at the foundation ofknowledge: the things that cannot be doubted.“Yet to bring this about I will not need to show that all myopinions are false, which is perhaps something I could neveraccomplish. But reason now persuades me that I should withholdmy assent no less carefully from opinions that are not completelycertain and indubitable than I would from those that are patentlyfalse. . . Undermining the foundations will cause whatever has beenbuilt upon them to crumble of its own accord.” (pp.9–10)Analytic method: requires some efforts from the reader. Goal:actual doubt.Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldDoubting the senses Dream-doubt The demonThree Stages of Doubt:1Doubting the senses2Dream doubt3Demon doubtDescartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldDoubting the senses Dream-doubt The demon1. Doubting the SensesThe senses are sometimes deceptive (e.g., sense-deception:stick broken in the water, etc.)“It is a mark of prudence never to place our complete trust inthose who have deceived us even once.” (p.10)Thus, we must doubt:any sense perceptioncolors, tastes, smells, etc.What we still have:that physical objects exist (even if they are not exactly as theylook like)that I have a body, and my actionsmathematicsDescartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldDoubting the senses Dream-doubt The demon2. Dream-doubt“How often does my evening slumber persuade me . . . that Iam here, clothed in my dressing gown . . . — when in fact I amlying undressed in bed! . . . There are no definitive signs bywhich to distinguish being awake from being asleep.” (p.10)We can never be sure in any particular situation whether weare dreaming or not.We cannot be sure in general whether we are always dreaming!Thus, we must doubt:corporeal nature in general — whether physical objects existshape, size, number, place of thingsphysics, astronomy, medicineWhat we still have:mathematics, logicDescartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldDoubting the senses Dream-doubt The demon3. The Demon“there exists a God who is able to do anything and by whomI, such as I am, have been created. How do I know that hedid not bring it about that there is no earth at all, . . . and yetbringing it about that all these things appear to me to existprecisely as they do now? . . . May I not be deceived everytime I add 2 and 3 or count the sides of a square?” (p.11)There could be an omnipotent God / demon who deceives meall the time.Descartes is not saying that there is such a demon; only thatwe cannot exclude that there is.Thus, we must doubt:mathematics, even logicWhat we still have: ?Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldDoubting the senses Dream-doubt The demonConclusion: “I am forced to admit that there is nothing amongthe things I once believed to be true which it is not permissible todoubt.” (p.12)Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldTrajectory of the Meditations:12345Cogito — the only thing which is demon-proof»Proving God’s existence»God is not a deceiver»Methodological principle: whatever I can clearly and distinctlyconceive is true»The physical world (at least some of it) existsDescartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldSince the dawn of time, philosophers have pondered about thenature of the soul. According to the idea of the twentieth century,called physicalism, everything can be described and explained byphysics, and whatever happens can be understood in a physicalway. The German philosopher of science, Carl Gustav Hempel hadan argument against physicalism. He theorized that the philosophyof physicalism is either not true or it is lacking content.Physicalism claims that everything can be described and explainedby physics, that every fact is a physical fact. Hempel raised anobjection against physicalism, according to which it is either falseor lacking content.Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldPreliminaries The argument Formal and objective reality P1 P2 P4 RecapWhat We KnowI am certain:That I existAbout my mental content — certain that these exist in mymind, but not whether or not they exist outside me.Moving outside:We need some way to prove that something exists outside ofthe mind.Strategy: show that there is something in my mind (thuswhose existence is certain) that must have been put there bysomething outside of my mind.This something will turn out to be the idea of God.Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldPreliminaries The argument Formal and objective reality P1 P2 P4 RecapThe Argument for God’s ExistenceP1 An idea must be caused by a being with at least asmuch formal reality as the idea has objective reality.P2 There exists in my mind an idea with an infiniteamount of objective reality (the idea of God).P3 Therefore, this idea must have been caused by abeing with an infinite amount of formal reality.P4 My mind has a finite amount of formal reality.) There exists some entity outside my mind whichhas an infinite amount of formal reality (God).Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldPreliminaries The argument Formal and objective reality P1 P2 P4 RecapFormal and Objective Reality12Objective reality: the kind of reality that belongs to anobject of thought. E.g., when you think about a cat, the cathas objective reality in your mind; similarly, when you thinkabout a unicorn, the unicorn also has objective reality in yourmind.Formal reality: the kind of reality that belongs toindependently existing things. E.g., the cat, beside havingobjective reality when you think of it, also has formal reality(it actually exists). The unicorn does not.Everything that can be thought of has objective realitySo far we only a know a few things that have formal reality —my mind and its ideas. (The ideas themselves have formalreality, what the ideas are about have objective reality — orso we would like it to be the case.)Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldPreliminaries The argument Formal and objective reality P1 P2 P4 RecapP1 : An idea must be caused by a thing that has at least asmuch formal reality as the idea has objective reality.A cause must have at least as much reality as its effect.Something can’t come from nothing; matter and energy can’tbe created or destroyed. (E.g., I cannot make 10lbs of glassfrom 5lbs of sand.)So, the cause of a thing (what we have at the start) must haveat least as much reality as the thing caused.Objective realities must be caused by formal realitiesWe need to explain not only that we have an idea, but whythis idea is an idea of what it is.This means that every idea (objective reality) has some cause.But this cause cannot be another idea; ideas (as objectiverealities) cannot cause anything.Thus, the amount of formal reality possessed by the cause ofmy idea must be at least as much as the objective realitypossessed by my idea.Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldPreliminaries The argument Formal and objective reality P1 P2 P4 RecapP2 : There exists in my mind an idea with infinite objectiverealityThe idea of God:infiniteall powerfulall knowingall perfectWe just need to check our mind; we can at least imagine sucha being, so such an objective reality exists.But what caused this idea? — According to the previous, itmust have been caused by something with an infinite amountof formal reality.Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldPreliminaries The argument Formal and objective reality P1 P2 P4 RecapP4 : My mind has a finite amount of formal realityIs my mind infinite and perfect?No:In that case, I would be omniscient, and I would not be able todoubt.But the First Meditation has shown that I am capable ofdoubting almost everything.Thus, my mind cannot have an infinite amount of formalreality.Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldPreliminaries The argument Formal and objective reality P1 P2 P4 RecapThe Argument for God’s ExistenceP1 An idea must be caused by a being with at least asmuch formal reality as the idea has objective reality.P2 There exists in my mind an idea with an infiniteamount of objective reality (the idea of God).P3 Therefore, this idea must have been caused by abeing with an infinite amount of formal reality.P4 My mind has a finite amount of formal reality.) There exists some entity outside my mind whichhas an infinite amount of formal reality (God).Since God is perfect, we also know that he is not a deceiver— being a deceiver would be an imperfection.Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldPreliminaries The argument Formal and objective reality P1 P2 P4 RecapSome General Remarks:The big idea:My mind has some amount of formal reality, bigger than 0,but less than infinite (since it can doubt)For all I know, my mind could have produced every idea Ihave. . . . . except one.The fact that I have an idea of God shows that God existsAnd since I am not God, it shows that something outside mymind exists.Note that we do not need any knowledge about the actual worldfor this proof! (It is a priori).Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldPreliminaries The argument Formal and objective reality P1 P2 P4 RecapWhere We Stand:123456Methodological doubt»Cogito»Proving God’s existence»God is not a deceiver»Methodological principle: whatever I can clearly and distinctlyconceive is true»The physical world (at least some of it) existsDescartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldGod is Not a DeceiverWe know that God exists, and he is perfect/infinite.We also know that to be a deceiver is not compatible withbeing perfect.Therefore, we have to agree that God is not a deceiver.“I acknowledge that it is impossible for God ever to deceive me, fortrickery or deception are always indicative of some imperfection.”(p.30, Meditation 4)Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldMethodological PrincipleI know that God is not a deceiver.To give me a faculty that I think is the most certain, and infact is not certain, would be to deceive me.Therefore, God would not have given me such a faculty.Thus, I can trust my faculty of judgment, if I am using itproperly.Principle: Clear and Distinct ConceptionIf I hold off from making a judgment when I do not perceive whatis true with sufficient clarity and distinctness, it is clear that I amacting properly and am not committing an error.Error only occurs when I judge something that I do not clearlyand distinctly conceive ( when my will extends more thanmy intellect)Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldWhat We KnowStrategy: to sort out what it is that I can clearly anddistinctly understand, and only call that knowledge. If I dothat, I will not commit error; I can attain certainty.What I do clearly and distinctly conceive:physical bodies existextension, shape, size, position, local motion, number.Thus, I can have physics (and astronomy, etc.) again, andmathematics (arithmetic, geometry. . . )Notice that all we do know is what physics uses — We canmeasure all these, and describe in the language ofmathematics.We do NOT know: colors, smells, sounds, tastes, pain, etc.Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldWhere We Are:SensedeceptionsDream-doubtDemon doubtcharacteristicsphysical objectsofwhatever I conceiveclearly and distinctlyis true: shape, size,number, position,motion. No colors,sounds, etc.existence of physicalobjects, physical sciences?mathematics, logicGod exists; he is nota deceiverDescartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldDreamsDreams and Non-Dreams“I now notice that there is a considerable difference between thesetwo; dreams are never joined by the memory with all the otheractions of life, as is the case with those actions that occur whenone is awake. For surely, if, while I am awake, someone weresuddenly to appear to me and then immediately disappear, asoccurs in dreams,. . . it is not without reason that I would judgehim to be a ghost or a phantom. . . . But when these thingshappen, and I notice distinctly where they come from, where theyare now, and when they come to me, and when I connect myperception of them without interruption with the whole rest of mylife, I am clearly certain that these perceptions have happened tome. . . while I was awake.” (p.50)Distinguishing mark of awakeness: memory.Descartes: Meditations on First PhilosophyMarch 11–14, 2014
Review Method Methodological doubt From there God’s existence Methodological Principle Physical worldSummarySensedeceptionscharacteristicsphysical objectsDream-doubtexistence of physicalobjects, physical sciencesDemon doubtofmathematics, logicDescartes: Meditations on First Philosophywhatever I conceiveclearly and distinctlyis true: shape, size,number, position,motion. No colors,sounds, etc.memory; in dreams,memory is not necessarily consistentGod exists; he is nota deceiverMarch 11–14, 2014
Trajectory of the Meditations: 1 Cogito — the only thing which is demon-proof » 2 Proving God’s existence » 3 God is not a deceiver » 4 Methodological principle: whatever I can clearly and distinctly conceive is true » 5 The physical world (at least some of it) exists Descartes: M
