This post is one of a serious that picks apart the arguments for god that can be found at the link below. This post addresses number 12:
If you don’t want to click over there to read it, the full argument goes like this:
12. The Argument from the Origin of the Idea of God
This argument, made famous by Rene Descartes, has a kinship to the ontological argument (13). It starts from the idea of God. But it does not claim that real being is part of the content of that idea, as the ontological argument does. Rather it seeks to show that only God himself could have caused this idea to arise in our minds.
It would be impossible for us to reproduce the whole context Descartes gives for this proof (see his third Meditation), and fruitless to follow his scholastic vocabulary. We give below the briefest summary and discussion.
We have ideas of many things.
These ideas must arise either from ourselves or from things outside us.
One of the ideas we have is the idea of God—an infinite, all-perfect being.
This idea could not have been caused by ourselves, because we know ourselves to be limited and imperfect, and no effect can be greater than its cause.
Therefore, the idea must have been caused by something outside us which has nothing less than the qualities contained in the idea of God.
But only God himself has those qualities.
Therefore God himself must be the cause of the idea we have of him.
Therefore God exists.
Consider the following common objection. The idea of God can easily arise like this: we notice degrees of perfection among finite beings—some are more perfect (or less imperfect) than others. And to reach the idea of God, we just project the scale upward and outward to infinity. Thus there seems to be no need for an actually existing God to account for the existence of the idea. All we need is the experience of things varying in degrees of perfection, and a mind capable of thinking away perceived limitations.
But is that really enough? How can we think away limitation or imperfection unless we first recognize it as such? And how can we recognize it as such unless we already have some notion of infinite perfection? To recognize things as imperfect or finite involves the possession of a standard in thought that makes the recognition possible.
Does that seem farfetched? It does not mean that toddlers spend their time thinking about God. But it does mean that, however late in life you use the standard, however long before it comes explicitly into consciousness, still, the standard must be there in order for you to use it. But where did it come from? Not from your experience of yourself or of the world that exists outside you. For the idea of infinite perfection is already presupposed in our thinking about all these things and judging them imperfect. Therefore none of them can be the origin of the idea of God; only God himself can be that.
I believe the Descartes argument that is mentioned at the top is summarised here:
ideas [of things] must arise either from ourselves or from things outside us.
We all have ideas, this is part of being human, sometimes our ideas are nonsense and sometimes they are correct. They are all out own. How does an idea come from outside of us when the idea happens inside our brain? Is there a demonstration of how an idea comes to us from outside of us? How do we tell the difference between the two idea types?
This idea [of an all-perfect god] could not have been caused by ourselves
With the failure to address how there are ideas that we don’t come up with ourselves, how could anyone support this claim? The claim is interesting, but its premise is not shown so why should the claim be accepted?
the idea must have been caused by something outside us
How? What is the mechanism? The author is running with the idea as though it’s true. Who came up with the idea that there are ideas that come from outside us? If that idea came from within someone, how could we know it to be true?
Therefore God exists.
Whose idea of god exists? Does every Christian describe the same god? Do they all exist? if a Christian’s idea of god is flawed or incorrect does that means it’s their own idea of god and not an external idea? Does that cancel out this argument?
It one believes the author, it seems that only the Christian god could have planted the idea of the Christian god into our minds because we’re too weak and limited in our thinking to invent that god ourselves? Really!?
One only has to read the Bible to see that the Christian god has many human characteristics, disproportionate vengeance, annihilation of the disliked, inconsistency. It’s all there.
If it’s specifically the Christian idea of god that has been given to humans from god, how come there are so many other gods that humans think about? Is the Christian god really that much more special that it would be impossible for humans to come up with it on their own?
As a final thought, I am genuinely astonished that this argument is presented seriously. In fact this argument makes me wonder if the whole list of 20 arguments is someone having a massive laugh at the expense of those Christians who buy it and reference it on an all too regular basis.