Okay, so in the previous video on Rene Descartes, remember that Descartes basically goes through this entire process where he uses this method known as radical skepticism in order to see if he could discover a truth that is a foundational belief which is 100% certain. A belief that you cannot doubt even if you tried. And so he claims to, using that methodology, he claims to have discovered that particular truth.
And that particular truth is known as the cogito argument, cogito from the Latin, which means I think. And so it can be summarized as I think, therefore I am. That is, his point was that even if I am being deceived by a malevolent being that has tricked me, and so everything that I believe is real, is an illusion, it's a deception.
According to Rene Descartes, there is still an I there. There is still a self that is being deceived. And so therefore, that truth, I think, therefore I am, is absolutely certain.
It is a belief that cannot be doubted. So I mentioned in the previous lesson that Descartes presents this as the foundational truth. But now he needs to go beyond that. He needs to take the next step and he needs to somehow provide an explanation as to how other types of beliefs that we have, how can those beliefs be rational?
Remember that he mentions in his... In his philosophy, he talks about beliefs that derive from the senses and beliefs that are based on mathematical truths. So how can I go from this basic foundational truth that the one belief that I know for certain is that I think, therefore I am.
How can I get from there? OK, so how can I get from that claim? to the rationality of beliefs that come from, let's say, the senses or from mathematics. So think of it in terms of a bridge, right, as you see there in the illustration.
What's going to connect those two things together? Because obviously you don't want to just stay with the I am, I exist. You haven't really said a whole lot at that point.
All you've said is that the only thing that is absolutely 100% certain is that you exist as a thinking being. But if that's all you say, you haven't really said a whole lot. So you need to kind of take the next step and make a bridge between that claim and other types of beliefs that serve as sources of...
beliefs that we hold as human beings, like beliefs that come from the senses and beliefs that are based on mathematical truths and so forth. So how is Descartes going to, let's put it this way, how is he going to make that bridge, right? What is the bridge that he's going to use to connect those two things together? And basically what Descartes does here is he presents what's called an argument for the existence of God.
That's going to sound, that sounds a little strange initially, right? But think of it this way. First of all, let me tell you what Descartes is not doing. Descartes is not presenting this argument as a means of trying to get people to become religious or to converge to Christianity or something like that.
Now Descartes himself was a committed Catholic. And so he did believe in God and he followed the Catholic faith. But his point in this argument is not to try to, in other words, he doesn't try to use this argument as a means of trying to get people to become religious or to get them to believe in God.
His point is that he's using belief in God as a proposition. or as a belief that enables him to explain how it's possible that you can have confidence in what's called the belief forming mechanisms that we have, right? So in general, what Descartes is going to do is he's going to present an argument for the existence of God. And this belief is used as the basis for the reliability of our knowledge of the world that we have. Okay, so here's the basic summary.
I'm going to give you the summary first, and then we'll kind of look at it in a little bit more detail. So the basic summary of... Descartes argument is going to be this he's going to start off with an argument which maintains that We have an innate idea right remember that earlier in an earlier video I emphasize that Rationalists believe that we have innate ideas so Descartes Proposes that we have an innate idea we have a belief that is already lodged in our minds It's already embedded within our consciousness And that is the idea of the most perfect being. Sometimes he calls that the idea of infinite substance. And that is what we normally mean by God, right?
So to quote by God, Descartes says, I mean a substance that is infinite, independent, supremely intelligent, and supremely powerful. And so what Descartes is going to do is he's going to sort of focus on that idea. And he's going to maintain that that idea cannot come from ourselves.
It cannot come from the world because when we think of ourselves, we recognize that we are finite and that we are imperfect. So the question is going to be, where does that idea come from? And then he's going to use that idea as a way of establishing our confidence in not in our beliefs that we employ to have knowledge about the world. Okay, so how does the argument basically work? Here we go, right?
Okay, so Descartes starts off, first of all, from the notion that we have an idea of God as an infinite and perfect being. Somehow, whenever you ask a person, how would you define God? Usually they'll say something like, well, God is perfect, or he's a perfect, God is a perfect.
being, God is all powerful, all good, you know, etc. Right. So the idea there is that Descartes starts off from the notion that we have an idea already embedded in our minds of a being as an infinite and perfect being.
Okay, so then he sort of wrestles with the question, okay, what is the cause of that idea? Now, what Descartes does in premises two and three that you have there in the screen before you, is he sort of focuses a little bit first. this question of what is it he focused on this idea of what's called causes and effect right and so the basic idea seems to be this for anything that exists in the world there's going to be some cause that brings that thing about and notice that premise number three emphasizes that there must be as much reality in the cause as there is in the effect so what does Descartes mean by that what he means can probably best be explained by giving you an illustration.
Suppose I'm holding a cup of hot coffee in my hand. What can I infer from that fact that I have hot coffee? Well, one thing that I can infer is that whatever caused the hot coffee must have itself been hot.
In other words, it came from a source that produced heat, and that's why the coffee is hot. And so that's why... that's what Descartes means in premise three, by saying that there must be as much reality in the cause as there is in the effect.
Now, what does he establish is because notice that premise four and this next premise here, premise number five, are highlighting the notion that the cause of the idea that I have in my mind of a perfect being cannot come from me. In other words, it can't come from the world because when I look at myself, I'm imperfect. I'm finite.
When I look at the world, the world is obviously characterized by imperfections and so forth. So the question that Descartes is sort of asking here is, what is the cause of the idea that I have of a perfect being, right? So if I go back to the previous slide, remember that That idea, therefore, right, it has to come from a cause that is itself perfect.
Think of that principle, right, that was... indicated in premise three that the reality and the cause must be greater than the reality and the effect. Okay, so with that in mind, Descartes is going to maintain that the best explanation for the fact that I have this concept or this idea of a perfect being in my mind whenever I think of God.
that the best explanation of that belief is that it must have been caused by something that is itself perfect and something that is itself infinite. And that is, of course, what we mean by God, right? So notice that premise number six, only an infinite and perfect being could be the cause of this idea. That follows from premises two and three. which I showed you in the previous slide.
So in his conclusion, Descartes maintains that therefore God, an infinite and perfect being, exists. Okay, so far so good. Now, what does this have to do with this whole business of rebuilding our confidence and knowledge? Well, this is how Descartes is going to use this argument.
Descartes is going to maintain that if God is absolutely perfect, it follows from that that God cannot be a deceiver, because it obviously contradicts the idea of a perfect being. So if God is not a deceiver, then I can have confidence that my belief-forming mechanisms are reliable when they are used correctly. Now what do I mean by belief- forming mechanisms?
What I mean by that is It refers to those things that we use all the time in order to develop or form beliefs. Like, for example, perception. We perceive things through our senses.
Calculation, right? We calculate things with our minds and so forth. Okay? Now, we can restate Descartes' argument in this way.
It's presented in the form of a deductive argument. If God is a perfect being, right? Premise number one. then my belief-forming mechanisms are reliable. Premise two, if my belief-forming mechanisms are reliable, then I am justified in my beliefs about reality.
Therefore, conclusion, if God is a perfect being, I am justified in my beliefs about reality. Okay, so you see how that works? Descartes uses the argument for the existence of God as the basis for having any kind of confidence in our beliefs.
When we say that this is knowledge and so forth, the only way that I can say that according to Descartes is because ultimately it can be traced back to the fact that God made human beings in such a way that their belief... forming mechanisms are generally reliable, obviously when they're used correctly. Okay, so that is the argument that's in general what Descartes is all about.
Have there been any criticisms of Descartes? Obviously there has been. I can't go into all of them here, but let me just highlight one brief criticism that for many philosophers they consider this to be a pretty strong critique of Descartes. Descartes' argument. And the criticism is that even though the argument that I just presented for you is interesting, some philosophers point out that this argument actually commits a fallacy.
It's known as the fallacy of begging the question. So what you have is you have what's called the problem of the Cartesian circle. In other words, because the argument assumes certain things that are used later on in the argument.
So here in a brief way, in a brief explanation is his argument. Descartes basically maintains that I can only trust my intellect is reliable after establishing God's existence. But notice that I need to trust my intellect in order to establish God's existence. So it seems that he's sort of caught in a little trap there. And so that seems to create a problem for his particular argument.
Nevertheless, that is the argument that Descartes presents. Hopefully that was clear. But if you have any questions, please reach out to me.