Chapter Five - Geometry and God

CHAPTER FIVE

Geometry and God

AFTER THE DREAMS, Descartes started treating math like a religion. Not in a superstitious way, but in the sense that it felt holy to him. Geometry wasn’t just about shapes or numbers. It was about certainty. You didn’t have to trust authority or tradition. You could prove it. You could walk someone through the logic and watch the truth unfold, step by step.

He wanted that same feeling everywhere.

Descartes started imagining a world where everything, science, philosophy, even theology, all worked like geometry. What if you could prove the existence of God the same way you prove the angles of a triangle? What if you could rebuild human knowledge from the ground up using nothing but reason?

He thought it was possible.

In his notebooks, Descartes started laying out early drafts of what would become his Method, a way of thinking built around radical clarity. Start with what you know for sure. Break everything down into smaller parts. Proceed logically. Leave nothing fuzzy. If it’s unclear, it’s not knowledge.

He also started applying this method to everything, including religion. That was dangerous. At the time, poking around too much in matters of faith could get you killed, especially if you did it publicly. Descartes wasn’t suicidal. He kept most of his ideas to himself for now, but he wasn’t hiding out of fear. He just wanted to get it right.

One of the biggest questions he tackled early was this: how do we even know God is real?

Not because someone told us. Not because the Bible says so. But logically.

He thought he could prove it.

Descartes believed that the very idea of a perfect being, the concept of God, had to come from something outside of us. He argued that the idea of a perfect, infinite being couldn’t have come from us, because an effect can’t contain more reality than its cause. So if the idea of perfection exists in our mind, something perfect must have put it there. That was his proof. If we can conceive of God, then God must be real.

It’s not airtight. Even at the time, people were poking holes in it. But Descartes didn’t think of it as a debate move. To him, it was foundational. If he could anchor his whole system to something eternal, something perfect and trustworthy, then the rest of it could be built on top.

So yes, Descartes wanted to invent a new science. But he also wanted to prove God. Not just for faith, but for structure. If God existed, and God wasn’t a liar, then the world must make sense. That was the idea. Reason wasn’t just useful. It was divine.

He wasn’t trying to erase religion. He was trying to rewire it.

Not with doctrine. Not with tradition. With math.