I found this chapter a lot more complicated than the previous two. It’s quite easy to become perplexed by the detail of a particular part and lose sight of the overall thread of the argument. Some of the parts I didn’t really understand, or wasn’t convinced by, and so when it comes to trying to piece it back together again, it eluded my grasp.
That said, when I consider it not as an argument intended to persuade the reader of God’s existence but as part of his method of establishing certainty then I find it easier to follow. That is, putting to one side beliefs about God, which I think would have fundamentally been a matter of faith for Descartes, and instead seeing that at this point in the Meditations we are at a stage where our existence as a thinking substance is established beyond doubt, but all we can say about our thoughts are that they seem to be of real things – not that they actually represent something real. The problem is getting back outside of our minds and so finding a way that ideas are caused by, or represent, something external.