Summary: Meditations on First Philosophy (page 3)

There must be as much reality in the total cause as in its effect, for whence could the effect derive its reality, if not from its cause ¹.
This is why nothingness cannot produce anything: nothing comes from nothing. Likewise, the more perfect cannot proceed from the less perfect.

From this principle concerning the relationship between cause and effect, Descartes deduces the existence of God. If the idea of God is in me, then God must exist, for only a perfect cause — God himself — can give rise to this perfect effect: the idea of God.

I could not have fabricated this idea myself — which would mean God does not exist — for that would imply that an imperfect cause could give rise to a perfect effect.

Descartes reformulates this argument using the concept of the infinite rather than perfection:

It must necessarily be concluded that God exists; for I would not have the idea of an infinite substance, I who am a finite being, if it had not been placed in me by some substance that is truly infinite ².

This idea of the infinite that I possess is not merely negative — as in the idea of that which is simply not finite.

Rather, it is an innate idea within me. God, in creating me, implanted this idea within me, much like a craftsman who leaves his mark on his work.

The idea of a perfect and infinite being within me proves both the existence and the perfection of God. This is why God cannot be a deceiver, for deception would be an imperfection.

In Book IV of Meditations on First Philosophy, Descartes, building on this, asks why we sometimes go astray. If God is perfect, should he not have created me incapable of error? Yet the fact remains that I err often.

We must therefore return to the causes of error — a task Descartes undertakes in this chapter devoted to truth and falsehood.

Error arises from the interplay of two faculties: the faculty of knowledge and free will — that is, my intellect and my will. The intellect, by itself, neither affirms nor denies anything; it merely conceives ideas, which then become the objects of affirmation or negation by the will.

The intellect is therefore perfect in the sense that it is never itself the source of error.

The will is also perfect in that it is infinite: I experience it to be so vast and so extensive that it is enclosed within no bounds ³, unlike memory or imagination, both of which are limited.

This perfection of the will is, above all, what makes me aware that I bear the image and likeness of God ⁴, for it is as great as that of God himself.

Descartes distinguishes free will from the freedom of indifference, epitomised by the famous Buridan's ass — the animal that, placed equidistant between food and water, perished because it was drawn no more to one than to the other.

This represents the lowest degree of freedom. The highest degree, by contrast, lies in deliberately choosing the best option:

In order for me to be free, it is not necessary for me to be indifferent to choosing either of the two opposites; rather, the more I incline towards one, knowing clearly that the good and the true lie within it, the freer I am ⁵.

Neither the faculty of willing nor the faculty of understanding, taken in isolation, is the cause of my errors.

Error arises from the fact that the will is infinite, whereas the intellect is not. This disparity leads us to assent to ideas over which our understanding has no grip.

As the will is far vaster and more extensive than the intellect, I do not confine it within the same limits, but instead extend it even to things I do not understand ⁶.

To avoid error, we need only apply the same principle that led Descartes to the cogito: suspend judgement — doubt, in order to arrive at indubitable truths.

¹ Ibid.
² p.128
³ p.150
⁴ p.151
⁵ p.152
⁶ p.153