Unfortunately, I'm unable to locate a good source to cite on these terms you see in the question title.

Below is a short abstract based on Google.

Natural light (lumen naturale), equivalent to lumen naturalis rationis, in medieval philosophy and theology denoted the ordinary cognitive powers of human reason unaided by the supernatural light of grace, lumen gratiae, or divine revelation, lumen fidei [ ... ]

From what I can gather

  1. Lumen naturale: Knowledge via human reason (philosophers)
  2. Lumen fidei: Knowledge via divine revelation (prophets)
  3. Lumen gratiae: Knowledge via divine grace (?)

Can someone go into some detail on these rather intriguing ideas. Muchas gracias.

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    See Augustine on divine illumination: "The mind needs to be enlightened by light from outside itself, so that it can participate in truth, because it is not itself the nature of truth." Commented Dec 20, 2022 at 12:06
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    For "lumen naturale" you can see Descartes' La recherche de la vérité par la lumière naturelle (The Search for Truth by Natural Light, 1630): the title means exactly: "to find the truth by way of human reason". Commented Dec 20, 2022 at 12:10
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    And yes, faith vs grace may mean: through the biblical revelation vs supernatural light immediately imparted to the soul by God Commented Dec 20, 2022 at 12:14
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    @MauroALLEGRANZA, much obliged. Lumen naturale is our God-given reason (re: Augustine, Aquinas, Doctor Solemnis, pace Duns Scotus). Lumen fidei is the heart of Abrahamic triad (revelation via prophets). Lumen gratiae is still not clear to me. The link you provided is a book and I'll have to read it to make a comment worth the pixels spent on it. Again, gracias.
    – Hudjefa
    Commented Dec 20, 2022 at 15:08
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    Maybe we can say that prophets received "true knowledge" directly by God or Spirit, and this is Lumen gratiae, why the believers received true knowledge through the texts (Bible) written by prophets, and this is Lumen fidei... But this is only my personal reconstruction, and maybe it is too much "rational" for this topic :-) Commented Dec 20, 2022 at 15:10

1 Answer 1


Lumen gratiae sounds of a piece with a notion I've seen in Reformed epistemology (this might seem more like a specialized Christian thesis, but several Reformed epistemologists are actually well-established adjuncts of analytic philosophy, so I think the topic can fit this SE well enough). That notion is the idea of common grace, something of a holdover from the heyday of divine illuminationism. Historically, illuminationism was relatively popular in Catholic circles until John Duns Scotus seemed to disconfirm it.

On the other hand, then, Descartes reintroduces a shadow of illuminationism with his otherwise "naturalistic" reasoning about how the God-concept is required to defeat the threat of demonic illusions. This leads to the question of the Cartesian circle. At any rate, illuminationism survives more straightforwardly in connection with John Calvin's talk of a sensus divinitatis. It is in connection with the graciousness of this sense that the doctrine of common grace emerges more conspicuously in Reformed circles, as an epistemic factor (even the "unregenerate" are capable of goodness and knowledge, on account of common grace, including the grace of having the total depravity of their created epistemic nature overridden by divine illumination).

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    So lumen gratiae is when a person who apparently doesn't deserve knowledge still attains it; a moral angle, it seems, to epistemology (only the good deserve knowledge).
    – Hudjefa
    Commented Dec 21, 2022 at 4:31
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    @AgentSmith, I would suspect that's the idea. "The sun shines on the just and the unjust alike," as they say. Granted, even the prophets/faithful were so by grace, according to the overall theory, but theirs was uncommon grace, in context. Commented Dec 21, 2022 at 10:05
  • Divine grace is a one in million affair, only a handful receive it. Those who do, some do I suppose, mustn't be flippant about it. This is serious shit, oui mon ami?
    – Hudjefa
    Commented Dec 22, 2022 at 4:43
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    @AgentSmith, the SEP article on the philosophy of humor says that one reason for negative philosophical portrayals of humor in antiquity, was the correlation between laughter and contempt in the Bible. It is dismaying to me that God was, and often still is, depicted as a humorless bastard who obsesses over torturing Its "enemies." I think an ironic, and hence half-serious, half-joking, God is more faithful to Its own glory than a God who takes Itself only too seriously. Commented Dec 22, 2022 at 9:20
  • Must read that article. SEP always pops up, at least used to, when I google. God is great!
    – Hudjefa
    Commented Dec 22, 2022 at 9:45

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