From the first two Meditations, Descartes has established at least one certainty: even if the objects he perceives may not exist as he thinks they do, the modes of thinking he uses to perceive and question them do exist.
In this Meditation, he tackles something I’m genuinely excited to explore - the existence of God.
The whole point of his six Meditations is to arrive at truths he can know with absolute certainty. One of the most widely accepted but rarely scrutinized assumptions is God’s existence. Descartes argues that if he can’t be certain about God, he can’t be certain about anything else.
A big mystery here is the origin of our ideas. Which thoughts originate from within us? Which are influenced by the outside world? And if all are influenced, then what even makes us us?
Take perception: if you sit next to a fireplace, you feel its warmth - you can’t “choose” not to feel it. That suggests there are elements of experience outside your control. If that’s the case, could there be another source - unknown to us - that also controls our senses and perceptions?
But here’s the problem: how do we know our perceptions reflect the true nature of things? With the naked eye, the sun looks small and close, but astronomers tell us it’s huge and incredibly far away. In other words, the image in our mind doesn’t resemble the object exactly. This may be what Descartes is getting at: our perceptions give us ideas of things, but not necessarily their actual essence.
Then comes his key argument: nothing can come from nothing, and something can only come from something of similar nature. Yet humans - finite, limited beings - somehow have the idea of an infinite, omnipotent, omniscient, perfectly good God. Where did that idea come from, if not from a being with those qualities?
At first, I thought: “Well, we can imagine opposites easily - just remove the limit and you get infinity.” But then I reconsidered. If humans had only ever known light, could they imagine darkness? That’s much harder. It’s like trying to picture a color that doesn’t exist - the mind goes blank.
So, if no attribute of perfection exists within us, Descartes says, the idea must have been placed there by something that does possess those attributes. Just as humans come from humans, and cats from cats, so too must the idea of God come from God.
For Descartes, that’s enough: the fact that he has the idea of a perfect being, which could not have originated from his imperfect self, is proof that such a being exists.
