René Descartes: Father of Modern Philosophy and Continental Rationalism by Leonard Peikoff

alright now let us turn to Rene Descartes 1596 to 1650 nowaday carte is more influential than Hobbes significantly so so please don't be deceived by the fact that I give him less time I give him less time only because in many ways his philosophy is less complex to present it is however overwhelmingly influential Descartes is acknowledged as the father of modern philosophy and as we'll see with ample justification he was brought up by the Jesuits he received a thorough scholastic training he is a devout Catholic nevertheless Descartes says he is going to make a fundamental new beginning in philosophy he is going he says to be much more fundamental in his approach than any other modern philosopher Hobbes for instance takes over modern science uncritically takes it for granted Descartes accepts the conclusions of modern science that is the scientific conclusions not materialism by the scientific conclusions but he says I want to question it I want to question everything right to the root I want to erect a philosophic system from scratch without taking over anything from other people uncritically and therefore this is going to be the beginning of a new era in philosophy now I may interject to say that as you will see de cartes ideas are not new his distinctive contribution is actually to institutionalize the primacy of consciousness that is to say the Platonic Augustinian viewpoint to plant it into the very heart of modern philosophy he is the father of the modern primacy of consciousness ever since you that viewpoint has been more explicit and virulent than ever before how did he do it that is our primary focus on Descartes this evening nowaday car like everyone else at this period is very conscious of method when it is early works his rules for the direction of the mind and another famous one is the discourse on method it tells us we must accept nothing blindly nothing arbitral not because we simply feel it not because others believe it not because our temperament points to we must be guided exclusively by objective reason now of course this sounds fine and it all depends on what he means by reason oh man he says are by nature equipped with reason reason is capable of knowing reality Hobbes is wrong reality is rational its intelligible it can be known by the human mind why then are men so confused so uncertain in such crime disagreement take her notice that when he went to school he what he was taught in one class was contradicted by what he was taught in another class and so he said that trouble is people just plunge in a haphazardly without a firm foundation without any systematic method and that's why they end up in such chronic disagreement well what method should we use well you shouldn't be surprised to know the Descartes says we must model philosophy on mathematics mathematics as the one science he says which enables us to achieve clear-cut indubitable certainty what enables mathematics to do this well it starts from basic self-evident axioms which are indubitable perfectly certain and proceeds logically to deduce their consequence and that he says is what we must do in philosophy that way we will achieve a philosophic system that is absolutely certain not a matter of opinion it will be a definitive statement of the truth to end all disagreement our philosophy in effect to end the crucial question of course is how are we going to get our fundamental axes now I point out to you they must be absolutely certain because everything else rests on them if there is one chance in a hundred in a thousand in a tree that a proposition is not true it is unacceptable to Descartes as an axiom because then of course it would infect all the rest of our knowledge with that same uncertainty well since Descartes there's only one way to proceed in our search for fundamental axes we must examine every idea we can think of we must search through the whole range of human thoughts and of every fact we must ask can this rationally be dota are there any rational grounds on which to doubt this idea now notice it has to be rational groans you can't just arbitrarily say this might be wrong you have to give a reason and if there's any grounds one chance in a thousand that the idea is wrong we have to simply abandon and look further now later we may come back and reinstate some of the ideas that we threw out at the beginning but we throw them out at the beginning because they are no good as the foundation of knowledge we want the indubitable the absolutely certain if we find nothing at all that fulfills this test when we should close up shop that's the end of philosophy period but if we find even one audit where it simply can't be dated then our base is established now this process is known as Cartesian doubt Cartesian being the adjectives from Dacre a Cartesian donor is supposed to be very different from a skeptical donor a skeptical doubter doubts because he delights in showing you can't be sure of anything a Cartesian doubter doubts because he's supposed to be desperate to find something that escapes the possibility of death Cartesian doubt if you want a formal definition the method of establishing a fundamental certainty by doubting everything you can conceive of any grounds for doubting the method of establishing a fundamental certainty by doubting everything you can conceive of any grounds for Delly now let me say this method is wrong it is disastrous if you approach philosophy this way only catastrophe can result as you will see in a woman well let us follow Descartes in the famous process of Cartesian Doug what can we don't well I'm going to read from Descartes he writes very clearly French and British philosophers right clearly has it gains German philosophy he stuff and I'm gonna interject constantly comments so try and keep clear when it's me and when it's Descartes he's gonna start from the most obvious point why not start from the most obvious Oh surely I cannot reasonably doubt that I am here seated by the fire attired in a dressing-gown having this paper in my hands and other similar matters and how could I deny that these hands and this body are mine well if not perhaps that I compare myself to certain places devoid of sense whose cerebellar are so trouble and clouded by the violent vapors of black bile in other words they're crazy that they constantly assure us that they think they are Kings when they are really quite poor or that they are clothed in purple when they are really without covering on court in other words there is such a thing as insanity insanity is characterized by vivid hallucinations and from delusions in both cases of course the person has no insight that's supposed to be one of the distinguishing characteristics between a psychotic and a neurotic and Yorick knows he's sick in a psychotic doesn't now says Descartes this phenomenon exists is it not possible that my belief that I am sitting seating here the dressing-gown and so on is a psychotic delusion or hallucination that happens to people how do I know it didn't happen to me is it possible not it probable but possible well there is one chance in a million that I'm a raving lunatic and that all this is simply a delusion if so I can't accept it because I want the indubitable that is sort of speak the insanity division of and now we go on quote at the same time I must remember that I am in the habit of sleeping and in my dreams representing to myself the same things are sometimes even less probable things then do those who are insane in their waking moments how often has it happened to me that in the night I dreamt that I found myself in this particular place that I was dressed and seated near the fire laughs in reality I was lying undressed in bed on reflection I see manifestly that there are no certain indications by which we may clearly distinguish wakefulness from sleep unquote people dream one of the characteristics of a dream is that you very rarely know that you're dreaming you take it as real you feel fear passion etc this to you is reality then you wake up with the start because there are that's just a dream well is it possible that you're dreaming right now that you're actually home in bed and I'm having a vivid dream of a lecture on Descartes and anyone would you'll wake up where else as Descartes as possible isn't if there's one chance in a thousand in a million can't be certain out that is the dream division now there's no you're saying the way to tell a difference between a dream and awake is to pinch yourself because of course Descartes will say how do you know you're really pinching yourself and not just dreaming that you're pinching yourself you see what I mean so he's going to assume the worst cuz he want certainty continue quote now let us assume that we are asleep and that all these particulars for instance that we open our eyes shake our head extend our hands and so on are but false delusions and let us reflect that possibly neither our hands nor her body are such as they appear to us to be on in other words maybe the whole thing is maybe the whole physical world is a dream or a huge hallucination after all can you trust the senses well even if you don't take the view that the senses are always wrong everybody says Descartes granted the senses are sometimes wrong and if the senses are sometimes deceptive how do you know in any particular case for certain that they're not deceptive in this particular case can't be certain of any conclusion about the material world therefore it might be a hallucination a delusion a dream a deception out we go on quote surely arithmetic geometry and other sciences of that kind which only treat up things that are very simple and very general you see which don't depend on the senses contains some measure of certainty and an element of the indubitable for whether I am awake or asleep two and three together always form five and the square can never have more than four sides and it does not seem possible the truth so clear and apparent can be suspected of any falsity unquote well you can imagine it seems self-evident that a square has four sides but people have been wrong about the self-evident they thought it was south over the earth was flat how do you know they're not wrong in this case is it possible well there's one chance in a thousand you can't be certain well suppose you say well but I'll give a proof I'll give a airtight argument premises leading to a conclusion the answer comes back people commit fallacies in their reasoning they reason invalidly and think honestly that they have arrived at the truth how do you know you didn't commit a fallacy is it possible one chance in a thousand Oh Descartes finds still in other grounds for doubt even of mathematics I have long had fixed in my mind to belief that an all-powerful God existed by whom I have been created such as I am how do I know that he has not brought it to pass that I am deceived every time I add two and three but possibly God has not desired that I does not desire that I should be nice to see for he is said to be supremely good well we cannot be certain that God is supremely good he may be an evil genius no less powerful and deceitful who has employed his whole energies in deceiving me I shall consider therefore that the heavens the earth colors figures sound and all other external things may be nothing but the illusions and dreams of which this demon has availed himself in order to Lake Tapps for my credulity unquote that's called des cartes demon how do you know it doesn't exist is it possible well I don't see why it's impossible he says that there could be an all-powerful wicked being who would delight in deceiving me and every time I add two and three and get five you rubs his hands and Glee that he took me in and of course there's a way of taking me in is to make two and three equals five seems so clear that we never think of questioning Descartes is not gonna be trapped by the deal quo at the end I feel constrained to confess that there is nothing in all that I formerly believed to be true of which I cannot in some measure doubt and doubt not merely through want of thought or through a levity but for reasons which are very powerful and maturely considered uncle you get the idea there are all these possible sources of our dreams hallucination delusion insanity sensory deception fallacies misidentification of the self-evident etc etc all that sort of speak symbolized by the demon the demon really represents the possibility of error now says Descartes the problem therefore is really this and this is the he doesn't say it but this is the actual meaning of Cartesian dough how can man ever achieve certainty because to say you're certain about something is to say you cannot possibly be wrong as it means to say you're a certain you simply can't be wrong about this you're a certain on the other hand man is a fallible being and a fallible being is being who can be wrong who is capable of error and therefore the problem posed by Cartesian dar is the problem how can a fallible being ever attain certainty on the face of it it seems like an obvious impossibility how can it be capable by nature of error ever reach of state of saying I'm incapable of error how can a fallible being attain certainty that's the problem posed by de cartes philosophy that the demon symbolizes now let's follow Descartes it seems that we're in a pretty hopeless state but wait I said says Descartes that I might be dreaming well I must exist in order to dream I said I might be thinking insanely even so I must exist in order to think insanely I said I might be deceived by an evil demon but I have to exist in order for him to deceive me I said I'm conscious of my inadequacies my ignorance my doubts I have to be to be conscious of you say I think incorrectly but the very fact that I think at all immediately establishes one thing even if all my thinking is wrong even if I reach total despair and I'm left with nothing but thoughts that I don't in order to doubt I must exist in order to think even if incorrectly I must exist I think therefore I am sloppy cogito ergo zoom which just means I think therefore I am that's the axiom called Descartes cogito the basic unquestionable premise the undoubtable is the existence of your self your mind or consciousness the very act of doubting your consciousness establishes your consciousness because to doubt is to display a certain kind of consciousness now notice that all the descartes as established is that his consciousness exists the argument works only for that one of his opponents tried to establish the body as say well and he said therefore I am ambulance oh they can't dismiss that as ridiculous because he said you might just be imagining that you're walking you might just be dreaming that you're walking you might just be thinking that you're walking the whole material world might be an illusion including your body but you can't just be dreaming or imagining that you're conscious because to dream or imagine means to be conscious they are certain kinds of consciousness if somebody says to you you just think you're thinking you say to him fine if I think I'm thinking I'm thinking because you see but I think he really means unconscious conscious in any form that's what he means by I think therefore the fundamental indubitable truth is my consciousness exists as uttered by Descartes or by any one of you who is conscious the fundamental axiom the basic premise the starting point of philosophy of all knowledge is the existence of consciousness now I cannot emphasize enough at this point in Descartes philosophy we do not yet have any grounds to believe that there is a physical world other people that you even have a body or the Descartes even as a body legs arms heart etc he knows only that he did cut as a consciousness exists in other words what he maintained is you can be certain of the existence of consciousness before you can know there is a physical external world consciousness has logical priority and therefore if we are to find I don't that there's an external world and Descartes thought there was one we must infer its existence somehow from the contents of consciousness we are not given existence directly we are given directly as our primary only consciousness this viewpoint is known as the prior certainty of consciousness for obvious reasons the place to start philosophically the easiest thing to know is your own consciousness it is a self-contained entity which you directly and immediately can discover and which we contradict ourselves to try to deny it's logically unassailable by the external world existence reality they are still doubtful for all we know at this stage there may be no external world at all there may be only our consciousness and that's it and everything else might be a figment of our imagination a gigantic deception perpetrated by the demon now I'll consider this consciousness could for our we know exist by itself without there being a reality it's a self-contained independent entity which does not require a reality metaphysical obviously therefore consciousness is not simply the Faculty for perceiving reality because if it were and the act of being conscious it would be aware of reality since we know consciousness first and don't know existence directly we are not in immediate contact with reality we have to try to prove that there's a reality we have to try to deduce it from our own consciousness from our axiom we are as I think you can see in an impossible position on the one hand consciousness metaphysically does not require reality and yet if we are to find out that there is a reality we have to deduce it from consciousness well how can you deduce reality from consciousness of consciousness doesn't require or imply a reality obviously you cannot now we'll see date day cards feeble attempt in a moment but it's so feeble that nobody of any significance followed a card in it because it's embarrassing now the upshot was that almost all philosophers accepted date cards prior certainty of consciousness and then there was a hopeless struggle to scrounge up a reality but they couldn't do it and so one by one and more and more reality dropped out of the picture all that existed was consciousness and it's experiences that has come to be called the problem of the external world on the problem of the external world bequeathed by Descartes is what makes you think there is one which many philosophers proclaim is insoluble now you know why I said that Descartes was the founder of the primacy of consciousness he himself believed in reality but his method of defending that belief rested on the prior certainty of consciousness in other words upon the independence of consciousness from reality upon the view that reality must be a derivative of consciousness which means upon the primacy of consciousness that was the fatal blow at the base of Descartes system from which mankind never recovered philosophic well what is wrong with the conclusion of the prior certainty of consciousness I don't think I have to tell you it is a logical impossibility for there to be a consciousness without existence otherwise what is it conscious of it is a logical impossibility for anyone to know that he is conscious without knowing that there is an existence otherwise what does he know he is conscious oh here I refer you to God's crucial statement existence exists and consciousness is the Faculty for perceiving that which exists existence and consciousness are both axioms they start off together in any full proper philosophy with existence first now you can see the disaster implicit in Cartesian doubt as a method it leads inevitably to the prior certainty of consciousness and therefore to the primacy of constants as to the error of Cartesian doubt itself as a method but that what led us to this conclusion that as I say I will discuss a lecture 12 but I'd like to simply note here in passing I want to clarify the enigmatic remark I made some weeks ago but I promised I'd clarify Descartes did not originate the cogito argument in slightly different form it was actually originated by Augustine as you should expect remember our emphasis Augustine's changing the focus of philosophy I emphasize from the outer from reality to the inner the soul our consciousness well as part of his philosophy Augustine had explicitly advocated the prior certainty of conscious and Descartes here is simply giving a somewhat different form and enormous prominence and emphasis to this Augustinian view point and since Augustine is really Plato may Catholic you can see that Descartes is fundamentally a platens well let's continue we want to try to establish the existence of the external world in which Descartes himself believed how are we going to do well Descartes says if only we can establish that there is no demon no perpetual deception being practice on us then we'll be entitled to trust our minds so the problem of the external world becomes the problem of getting rid of the demon how will we prove there is no D well says Dacre only if we can prove that there's an all-powerful and good God watching over us then we'll be ok because a perfect God wouldn't permit demons to go around deceiving us and of course he wasn't stoop to deception himself therefore our scenario goes from our consciousness as item 1 to have come into existence in to item 2 God's consciousness from the mobile consciousness to the amoral find an infinite consciousness before we can finally get to the external world hopefully at this point Descartes launches into a whole series of arguments for the existence of God they are standard of course he can't use the argument from design you know the argument the whole world is so orderly therefore God must have created because he doesn't know there's a world yet but he picks up the ones that he can from ancient and medieval philosophy he can say Here I am somebody must have created me I didn't so it must be God he uses st. Anselm's ontological argument which he thinks is terrific yes I'll give you a brief taste I've called the argument from the cause of the idea of God you get that the argument from the cause of the idea of God and that argument goes like this I have an idea of God his definition of God by the way is quote a substance who has infinite eternal immutable independent all-knowing all-powerful and which created everything which exists unquote now there was a perfect Christian God now he says this is the idea of a perfect Pig where did I get this idea what caused it in me did I make it up myself no why not because the cause of anything must be at least as perfect as the effect the less perfect cause the more perfect how do you know that the less perfect can't cause the more perfect says Descartes and in pregnant uh turns that is quote clear and distinct you remember that phrase from the storix here it's coming now the less perfect the less real can't cause do more perfect dome arrow real that is quote clear and distinct obvious self Evan now ever an imperfect and finite that's obvious consequently I couldn't cause this idea because this is an idea of an absolutely perfect being and therefore itself shares in absolute perfection therefore only an absolutely perfect being could have caused it in me and therefore it did and therefore there must be such a being therefore God exists QED the idea of God he says is quote the mark of the workman impressed on his work unquote it's in effect as God turns out each soul he stands his trademark on and the trademark is the idea of God and then when the soul becomes adults and introspects it finds the trademark and that's the idea of God who from the perfection of the trademark infers the perfection of God as the cause no I want simply I wouldn't bother to criticize this argument by simply point out what a platonic argument it is the more perfect can't be caused by the last perfect how does that follow well only if you accept Plato's view of degrees of reality and degrees of perfection there's a higher a really real really perfect world and all world which is a dependent derivative not as real or perfect and since the higher our world is true reality it is the source of the imperfect reflections down here things down here we get goodnesses they have by sharing in the rays emanating from beyond now you see this is the essence of this argument our idea of God is a ray of perfection shining in our imperfect persons so it must come from the earth now that was he now takes the platonic metaphysics as self-evident and as other arguments are typical well let's continue you can read modern commentators they delight to demolish his arguments for God so we don't have to waste time on now are we almost have a physical world in existence first the soil then God now we're on the threshold of establishing that there is a reality after all says Descartes God gave me all my powers including my cognitive powers he would never have given me the power to judge truth or falsehood unless I could trust myself God wouldn't purposely deceived me he wouldn't deliberately make me wrong because God is not a deceiver how do we know because God is perfect and of course anybody who engages in deceit is obviously not perfect now I know here in passing the fantastic introduction of valued judgments as though they are self-evident at a point where we don't yet even know that there is a physical world we are nevertheless in a position to pass value judgments on life but that is simply an alien common notice also that Descartes therefore believes that the validity of human consciousness depends upon God if there weren't a good God we couldn't trust our minds this is a blatantly Augustinian element as against Aquinas man's mind is not self Aladin it must be validated from beyond by God and that is of course another reflection of the true augustinianism of Dacre well we're not all ready for the physical world now we can trust ourselves Descartes says somewhere here and one of his books has six MIT meditations and my mind gets to the meditation number six after a whole long essay and he says words to the effect I don't remember the exact words but the ideas there remains only to consider whether there is a physical world that the last question I never fail well how do we get the physical world into the picture well says Descartes you have to grant that we perceive things which appear to be physical objects now we don't cause these experiences in ourselves because we can't alter them and well you simply can't Francis will the sight of me away and therefore the cars must be of our experiences must be somehow outside of us well you might ask could you God directly cause our experiences in us without the intervention of any physical world Noah says Descartes what you ask is it because we perceive directly a material world no obviously we don't if we directly perceived in material world we wouldn't have the primacy the prior certainty of consciousness Noah says Descartes we know that God doesn't cause our experiences directly in us that they must come from the material world because we conceive matter as clearly and distinctly different from God why do we on this philosophy no answer we just do therefore a material world exists because otherwise God would be deceiving us in something that is quite clear and distinct to us now you don't have to be surprised that nobody followed this particular route to an external world it is much better it's out there to get rid of reality right off the bat than to drag it in in this feeble arbitrary way now I would like you to observe how hopeless this whole poach of Descartes is from the following aspect he's gone through all of this argumentation and a good part of it I left out as to why we can trust our minds all the arguments for God and if there's God he wouldn't deceive us and therefore we can trust our mind in the oil business now he's satisfied yes we can trust our minds suppose you grant all of his argumentation every step of it from the cogito ron is impeccable to the human mind you can't find a thing wrong with has he therefore validated the human mind obviously not if there were a demon which is his hypothesis or the beginning at the end of this whole incredible chain of reasoning as Descartes says neither have validated the human mind the demon would simply sit back and chuckle to himself I really took him in that time now the wider point here is there can be no such thing as an argument to prove that the mind is reliable if you call in question the reliability of the mind the validity of the mind what do you propose to use to answer the question if you say you cannot trust human arguments now here's an argument to show that you can trust them after all peak you can't trust them you can't trust them period and that cuts out your own argument either the validity of the human mind is an axiom or all is lost it cannot be established by reasoning because reasoning is an act of that very mind and when I say all is lost I mean all because as later philosophers were quick to point out even the kobito itself does not stand on de cartes premises how do you know that just because I think therefore I am de cartes answer is well I think therefore I am must be true it is so clear and distinct but the answer is it's no clearer and distinct her than two plus three equals five or a square has four sides and all these cases the opposite is a contradiction but if we can't trust our minds if something could be blatantly contradictory to us and nevertheless be correct then we cannot trust anything including even the statement that we have minds or engage in doubts we were wiped out entirely in this way Descartes is really the source of all modern skepticism although he claims to be putting an end to skepticism he really more than anybody entrenched ancient skepticism deeply into all modern philosophy as typical for simply accepted the method of Cartesian throughout the coquito us arbitrary and ended as a complete ancient skeptic if in one respect Descartes is the father of idealism in other words of the primacy of consciousness and of the mentality which dispenses with or degrades the external world in another sense he's the true father of modern skepticism so in one stroke you see he reinstituted the Sophists and Plato Plato via the primacy of consciousness and caused the door to Aristotle oh and now let's look at des cartes epistemology and then come back for a few final words on one more aspect of his metaphysics des cartes epistemology are the senses valid no Descartes accepts the primary secondary quality distinction the senses deceive us they do not give us any knowledge of the real nature of the material world all it is actually real in his terms is extension ext en si Oh an extension which means three dimensionality spread openness in space with the appropriate Associated characteristic size shape quantity motion the census says dake are useful for practical purposes of living but they do not give us objective knowledge about reality to gain to knowledge what do we do well as we said at the outset we must gain model ourselves on mathematics we need self-evident axioms or where do we get our basic premises from well in theory there's only three choices you look outward to get your basic axioms our Aristotle you look upward our honesty or you look inward our player now Descartes has rejected the census as a source of axioms he is being very modern in secular and therefore he rejects God as the source of actions and the only choice is you look inward you have to introspect to get your basic premises does this mean then that there are ideas in the mind apart from sensory data ideas acquired by some means other than the senses yes tako how did we get them we are born with them they are innate and here of course Descartes follows Plato although he does not believe that all knowledge is in only certain crucial fundamentals for instance the idea of God is innate certain mathematical ideas and so on of course Descartes does not believe in the pre-existence of the soil that's prohibited by Catholic dogma and he therefore follows the Augustinian view that innate ideas are our heritage from God so how do we do to acquire knowledge we look inward and try to discover our innate ideas notice that an idea has become in effect a self-contained thing inside our minds that we rummage around to find an idea is no longer a form of awareness of reality and of course the primacy of consciousness that Descartes subscribes to forbids the idea that an idea is a form of awareness of reality yes an idea where an awareness of reality then whenever we thought I had an idea we'd be aware of reality there could be no prior certainty of consciousness on the other hand if an idea is an awareness of reality we'd have to be aware of reality to get it so it couldn't be unique in other words the real epistemological expression the epistemological expression of the primacy of consciousness is innate ideas and that's why Plato believed in them and that's why iCard believes it consciousness has to have its own domain its own independent content to focus on detached altogether from reality that's what innate ideas serve at Bicester Millan well how do we tell these innate ideas how do we distinguish them from the falsehoods and confusions that we have acquired through the Census and through commerce with other people because by the time we come to philosophize we're growing up when our mind is a grab bag for Descartes of conventional notions and popular prejudices and true innate ideas how do we distinguish the authentic article coming from God from the arbitrary prejudices beliefs and so on can you do it by observing reality and checking or not that's up the answer is it must be something in the nature of the idea itself that certifies that it's the true article there are real innate rd what is it it's clear understate quote the things which we can see very clearly and distinctly are all true unquote he has the grace to add that there is some difficulty in ascertaining what those are Maya what does this mean now of course Descartes himself did not advocate subjectivism he thought is clear and distinct innate ideas were objectively self-evident but in fact of course this has led to the idea that axioms are subjective because there's now no way of validating axioms by reference to Sense experience by reference to reality you see in day card whenever he gets stuck he has a clear and distinct intuition and then he goes on from there he wants to prove God and he gets stuck well the perfect can't be caused by the imperfect clear and distinct and on he goes he wants to prove the external world clear indistinct there must be different from God and so with many other examples of that now the moderns of course draw from that the conclusion that there are axioms and so the fight is paused between the Cartesians who say yes there are clear and distinct in a taxi UM's and the other side who says all it's all ridiculous subjectivism there are no self-evident acts now of course Descartes is right that knowledge requires self-evident axioms but the crucial thing is it must be axioms which are objectively based on reality which means on the direct testimony of the senses everything else has to be logically proved now in this sense Aristotle points the right direction axiom for Aristotle must be reducible to the directly perceivable but of course that's the primacy of existence approach which Descartes rejects out of hand and the result of de cartes approaches that pretty soon more and more of his more careless followers begin to take more and more of the most grotesquely arbitrary ideas as clear and just seem to me therefore this is my accent pretty soon altruism becomes self-evident Oh must be a God after all I clearly and just think to conceive that somebody must have created the world etc and then of course the reaction sets in Hobbes takes over or his followers and says oh it's all linguistic it's all arbitrary there is no objective self evidence so you see the choice you're giving Descartes posing as a champion of objectivity comes up with axioms as being clear and distinct and innate which means unbasic Hobbes says oh they're all arbitrary and linguistic which means on based on reality on the crucial point they agree what then is the total method of knowledge for Descartes you look inward you find you're clear and distinct ideas you do this by a process that he calls intuition intuition for him is the process of grasping clear and distinct ideas and then you deduce their consequences if you get stopped at some point you simply have a new intuition of a clear and distinct idea crank up the Machine and go on again so basic knowledge is in Asia the mind and is grasped by direct introspection or as he calls it intuition and deduction there from now this as you know is the model of rationalism the idea that reason alone reason here being the Faculty which does intuition and deduction reason alone leads to all knowledge the senses observation inductive generalization our for Descartes basically unimportant they may be useful for practical purposes they may even be fruitful and suggesting ideas to us to refer to our intuition to certify they may remind us of our innate ideas ala Plato about the senses and induction do not tell us what reality is like that we find out from innate ideas how do we know our innate ideas are true since they're not based on observation well of course Descartes answers God gave them to us and God wouldn't deceive us now his followers quickly pointed out the hopeless circularity of this answer he has to use his innate ideas to prove that there's a god and then used the God to prove that he can rely on his innate ideas which is a hopeless circle from which he never extricated himself now I notice how consistent date card is epistemologically and metaphysically within the framework of the primacy of consciousness if consciousness is the Faculty of thinking as he says it is and thinking is the awareness of reality then consciousness is not independent of reality and there can be no prior certainty but if there is a prior certainty of consciousness then thinking must have some object other than reality some aspect of consciousness as its content otherwise consciousness is not self-sufficient it must have some content of its own apart from reality and Descartes says yes and that content is innate ideas so in other words the primacy of consciousness metaphysically necessarily implies the breach of consciousness from existence epistemological the primacy of conscious as metaphysically necessarily implies the breach of consciousness from existence epistemology and that breach in term reinforces the primacy of consciousness because the person says I never perceive reality how do I know it's there all I know is consciousness so you have a vicious circle from which there was no escape except by saying the starting point is existence exists now let's say as I said I would a few last words on des cartes metaphysics again specifically on the mind-body question for which he is famous they're all for Descartes two things which exist then consciousness and matter they can't cause these two each substances and therefore he is regarded as a dualist in metaphysics because there are two kinds of things consciousness and matter two essential components to reality as against Hobbes who says that only matter exists or has against Plato who tends to deny that the physical world is actually real Descartes think both are real physical world and conscience he calls them each substance and his definition of substance is quote a thing which exists in such a way as to stand in need of nothing beyond itself in order to exist a thing which exists in such a way as to stand in need of nothing beyond itself in order to exist you can see the trouble in this definition if consciousness is therefore a substance so the two substances are the mind substance on the body substance what Descartes calls the Rays Kogi tans the thinking thing and the Rays extension the spread out thing or the extended thing and he adds that really God is the only substance because everything else depends on God but we can admit that complexity so we have two completely self-contained this is all worlds independent of each other unconnected a kind of metaphysical essay fair in which each leaves the other alone neither requires the others neuroses Descartes I have achieved a terrific thing by the splintering the universe into divisions because I have found a way of retaining thought purpose freewill in a world in which matter is necessarily mechanistically determined by physical laws matter I agree to raise extension is a completely material mechanical system just as Hobbes and the scientists claimed it is now he says I believe in God and that there is final causes there is a purpose to everything that happens even in the physical world but final causes are inscrutable to human beings and therefore as scientists we should look for them we should content ourselves with ordinary natural scientific laws in that sense scientists are absolutely right but he says that God introduced a certain quantity of motion into the world when he created it and then he withdrew and from then on at Abbes the laws of modern science and therefore scientists can study it as scientists with impunity now he says not only have I preserved the domain of modern science I have escaped the catastrophe of Hobbes I have found a place for mine in the world of matter and therefore for all the things which are crucial to our Catholic religion mind is purposeful so even though matter operates only by mechanism mind is teleological mind thinks that's the essence of consciousness it's the thinking thing the Rays called you tens so we're not simply as a Hobbes said creatures whose brains oscillate according to stimuli we can think and come to objective conclusions mind he says free will he's a strong believer in volition because he has a clear and distinct idea of it as to the question of how you reconcile a gods causation of everything with free will he says simply this is incomprehensible to man we shouldn't consider the question mind is since it's entirely independent of matter it can exist without matter and this is the best proof of immortality ever offered in a word we make everybody happy he says the scientists and the religion is both we carve the universe in two we intersect render unto God the things that are gods the mind and unto Galilei are the things that are Galileo's the material world thus des cartes famous reconciliation of science and religion notice by the way that freewill purpose and the power of thought get in under the power of religion and have been associated with it ever since so to this day if you say you believe in free will the power of thought or the reality of purpose in human psychology most philosophers and almost all psychologists routinely say oh that's some religious crackpot that's the legacy of Descartes you see while it come finally to man how do we make sense of man he is the creature who is a union of the two substances of mind and body and the shocking thing is that in the case of Mandy's to utterly disparate independent substances can actually influence each other they can't interact as it goes for instance in saint's perception something physical strikes my mechanical body after the appropriate jiggling and mechanical oscillations suddenly an event leaps the gap and in the raised kogi tends there is a mental experience that's body influencing morning and of course the other way around watch I'm now going to describe to you a mental event namely an intense desire to raise my right arm straight in the air now watch there goes the raised extension following straight up in the air so obviously there's two-way interaction now the question is how can there be interaction between these two absolutely separate absolutely different completely independent substances this is known as the problem of interaction and the problem is Descartes told us the body or some mechanical system a mechanical system which moves only on physical contact the mind is not in space it's not physical and therefore it can't contact the body physically how can the mind move the body and moreover if it does think of the trouble were in if the mind moves the body the body is not exclusively in the realm of mechanics and they're all the materialists and physical scientists scream that we've introduced supernatural influences but if the mind doesn't influence the body that means the soul is impotent there is really no free action our mind is just a little helpless nothing that has thoughts which no influence on our actions and of course all the theologians have a fit so we're in bad trouble that's the problem of interaction now I have to say parenthetically that it this is not a legitimate philosophic problem unless you said as Descartes did to absolutely separate absolutely independent substances and then try and wonder how in the hell are you going to get them back together again there is simply no justification for his assumption that there's nothing in common between mind and mind if you reject de cartes arbitrary split which is generated by the primacy of consciousness now de cartes answer is interactions possible because God has United these two substances marvelously which means it is metaphysically incomprehensible but he says at least the problem goes no further than man animals don't have to have souls for religious purposes and therefore let us say that animals are strictly mechanical systems devoid of consciousness which Descartes proceeded to say your cat or dog all are devoid of consciousness they're little automata little mechanistic systems they are aware of nothing they feel no pain they feel no nothing where we have to get as little consciousness as we can you see because it simply is a marvelous miracle but it's a miracle that we can't override you see and therefore let's confine now of course a whole school of materialists immediately Rosen said if we can get rid of consciousness in animals and explain all of their actions exclusively by materialistic factors in dispensed with consciousness why not with man - and so Descartes is the father of modern materialism as well now one philosopher Gilbert Ryle an arch materialist who was the ethic still is the editor of mind magazine today in which he satirize Day cards view but with a very clever satyric of description he says Descartes holds the view of man of the ghost in the machine and that is correct there is this spiritual entity it's a ghost devoid of matter rattling around inside this mechanical system and never the twain shall meet except by a miracle now of course royal jaws the conclusion down with consciousness and let's be behaviorist but his characterization is correct in details des cartes theory becomes even more fantastic he thought he found a point in the body where the Rays Coby tans meets the Rays extension the pineal gland needless to say that left him open to fantastic ridicule and his followers were eager to find some way out of this impossible theory of interaction since they accepted all of his premises interaction was incomprehensible to them also and therefore they drew the conclusion there not one and all but all but one that drew the conclusion we must explain the appearance of interaction while denying the fact of interaction there really is no interaction now let's explain why it looks like there is the occasion list for instance a very minor school mr. Langston Malibu argued like this they said there is no interaction when it appears to us that a physical event in the body is causing a mental experience in the mind what actually happens is on the occasion of the physical stimulus God intervenes and directly arouses the experience in our mind and on the occasion of an act of will in the mind God intervenes and causes the body to move and therefore to the naive observer it looks like the mind influences the body and vice versa but actually God is the cause of the apparent interaction that's called occasion with music now this of course is bizarre and Spinoza and Leibniz set themselves as one of their tasks to explain the appearance of interaction more sensibly while also denying the fact we'll look at that next week now I think you can see the disasters implicit in des cartes philosophy from different aspects use at once the father of modern idealism modern materialism modern skepticism in other words of every destructive trend in all the subsequent centuries you see why he's called the father of modern philosophy he is as to ethics by the way Descartes did nothing in that field or nothing originally he was not particularly interested in ethics or politics if you could classify an Batali's in effect a combination Catholic and stoic but he has no special influence in these areas now I think you get a better idea why objectivism stresses that the two fundamental axioms of philosophy are existence and consciousness with existence coming first if you start with consciousness you get Dacre if you deny consciousness you get Hobbes in either case you get catastrophe what is the result of the disaster if there's no consciousness our Hobbes then man is cut off from reality incapable of knowing it if reality is in doubt as in Descartes the same result in both cases you have a fundamental breach between man's mind and reality either by denying the mind or by casting doubt on reality and this breach between man's mind and reality is the fundamental theme uniting Hobbes in Descartes this is the theme we will see intensified and developed next week or next lecture when we look at three followers of Descartes Spinoza live that's Locke thank you very much [Applause] you what I'll give some examples of de currents application of mathematics to philosophy I already have given you the major one namely the concept of deduction from self-evident axioms as the essence of the method in philosophy another one which is essentially a mathematical method as against the observational inductive approach to knowledge another of course is de cartes emphasis on quantity as the true feature of reality metaphysically the primary qualities being the quantitative ones you see and of course there are many more in detail Descartes himself was an accomplished mathematician but we're not here to discuss his achievements in mathematics

Channel: Ayn Rand Institute

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Keywords: history of philosophy, history, philosophy, history of western philosophy, western philosophy, leonard peikoff, ayn rand, ayn rand institute, objectivism, objectivist, political theory, modern philosophy, ancient philosophy, school of life, crash course, lecture, educational video, secular humanism, rene descartes, descartes, Continental Rationalism, Cogito argument, i think therefore i am, mind-body problem, mind body problem

Id: D6C9h7tAk58

Length: 66min 33sec (3993 seconds)

Published: Fri May 01 2020