That’s wonderful: no doubt you will do very well on the project. I did a little work on the blog and added you as an inspiration in the subtitle, seeing as you’ve helped me refine it. Do you think this is better?

I completely agree that Descartes wants a system from the ground up, and I did not mean to suggest Descartes said God exists because we think of God: it’s instead more like that God must exist because we can think of God, and the God Whom Must Exist would exist even if we didn’t think about Him (the mistake is treating “must” and “because” like similes). For me, I always understood Descartes as making a key move here to escape his argument from being self-contained and grounded on nothing outside of itself: he wants to find axioms, per se. If his system is self-contained, there would be reason to doubt it.

I agree: Descartes is often misunderstood to being saying that x exists because we think about it. Absolutely, but at the same time, I took Descartes argument from thought to God to play a key role of “providing reason to think” thought is grounded not just on itself (and instead on an "ultimate ground of being"). Descartes erects a convincing system, but the final and most difficult step is justifying that system as not simply being “internally consistent” versus axiomatic. Gödel, much later, shows this can’t be done, but it arguably can be if God Exists (though perhaps not convincingly). That’s what I always took Descartes as trying to do, but it is not an interpretation I can back up with years of scholarship. It could easily be wrong.