Now it is indeed evident by the light of nature that there must be at least as much [reality] in the efficient and total cause as there is in the effect of that same cause. For whence, I ask, could an effect get its reality, if not from its cause? And how could the cause give the reality to the effect, unless it also possessed that reality? Hence it follows that something cannot come into being out of nothing, and also that what is more perfect (that is, what contains in itself more reality) cannot come into being from what is less perfect.

Descartes' Meditations, III, 14.

  • 1
    Do you have a citation for this quote? Feb 5, 2019 at 18:22
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    He claims that the "natural light" (intuition) makes it evident that the cause must be at least as "real" as the effect, and then deduces that the more perfect cannot come into being from the less perfect. This is in preparation for deducing that the sum of all perfections (God) must exist. Alas, "the more perfect cannot come from the less perfect" seems to be rather obviously false today (in the light of self-organization and evolution), so the "natural light" may not have been as bright here as Descartes supposed.
    – Conifold
    Feb 5, 2019 at 20:49

2 Answers 2


Descartes' Meditations, III, 14.

In a nutshell, form where we humans can "receive" the idea of

a God [sovereign], eternal, infinite, [immutable], all-knowing, all-powerful, and the creator of all things that are out of himself [?]

This idea [the effect] must be produced by something [its cause] that has at least as much "reality" as the idea itself.

Thus, the idea of an infinite being cannot be produced from ourselves, finite [less perfect] human beings; it must have its source in an infinite being [more perfect].

See Descartes' Theory of Ideas : Ideas and The Formal-Objective Reality Distinction :

Descartes’ analysis [in the Third Meditation] of [the idea of God] begins with his focusing on the fact that the idea represents to him an infinite substance (AT VII 45; CSM II 31). [...] He concludes that there must be some being that in fact possesses the requisite level of formal reality, which in this case will be greater than that of a finite substance.

See also Descartes' Epistemology and Descartes' Ontological Argument.


Descartes is assuming a metaphysical principle, one that dates back at least as far as Plato, and that seems to have at least common-sense validity, that something less perfect cannot be the source of something more perfect. In other words, copies degrade, they never improve. (In general this does match much of our experience in the world. A copy of a copy increasingly loses fidelity --on a photocopier, or in a computer system, and so forth. At most it can be as good as its source, not better.)

With that as an assumption, Descartes argues that something more real cannot come from something less real. Because of this, the universe needs to have a source. It cannot have come from nothingness. And the source needs to be at least as good and full and perfect as the best thing in the universe.

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    But Descartes is speaking [in the quoted topic] of "source of ideas" and not of the universe. See D's Theory of Ideas : Ideas and The Formal-Objective Reality Distinction : "Descartes’ Third Meditation examination of his idea of God reveals that the objective reality that it contains or possesses is that associated with an infinite substance. At the very least, the view is that the idea of God contains a level of objective reality that is greater than that contained in an idea representing a finite substance." Feb 6, 2019 at 10:46
  • @MauroALLEGRANZA If you're an idealist, that's the same thing :) Feb 6, 2019 at 14:02

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