Knowing “clearly” vs. “with firm certitude” in Vat. I Session 3, Ch. 2 no. 1,3

Session III, c. 2 of Vatican I argues that by reason, God can be clearly known, but also that revelation was given so that God could be known by everyone with firm certitude (read the whole thing, I’m summarizing here). The students pounced on this as a contradiction: how can one add firm certitude to something already clearly known?

There are two options:

1.) Firm certitude adds nothing to what is clearly known. i.e. the two are synonymous and interchangeable. In this case we would have to read the certitude clause entirely in conjunction with the previous clause. Before revelation, some men could have certitude/ clear knowledge about God, and afterwards everybody could. Or perhaps the sense is this, though by reason God could be clearly known by some, revelation does not make God known to everybody by watering down the certitude that could be achieved. Revelation does not, say, dumb down natural reason into a popular doctrine that is easier to understand but less intrinsically compelling.

2.) Firm certitude adds something to what is clearly known. Perhaps the clarity of reason, at least about God, never rises to the level of a firm certitude. We see things clearly, but in a light that we know is only human; or perhaps we realize that the clarity we can reach by natural reason is a delicate thing, not an unshakable state that could stand up to any and every assault. “Firm” (like “solid”) is a state that is relative to the forces that are acting on a thing: the same rope-bridge that a walking man would consider very firm might be considered flimsy by a man who want to ride an elephant across it. Perhaps clearly is said relative to our own power of vision whereas with firm certitude is said relative to the calamities or assaults that might befall our knowledge.


  1. Charles said,

    November 27, 2012 at 10:57 am

    Could it also be that by natural reason only some will have a clear knowledge that God exists (by a rationally compelling demonstration), but that by faith all can have the firm certitude that God exists without the need for demonstration? In the creed we do not say “Credo Deum esse” but rather “Credo in Deum”. I have read Fathers that make a big deal of this difference, noting that to believe in God is to accept his revelation, whereas to believe that God exists is indifferent to his revelation. I would see the “firm certitude” as applying to those who know that God exists by faith (for faith is firm and certain) whereas clear knowledge belongs to one who has a demonstration.

    • November 27, 2012 at 12:46 pm

      I hadn’t thought of that: perhaps “clear” and “firm and certain” differ by the mode by which we attain the object: whether by reasoning or a testimony, respectively. A testimony involves agreement to the one testifying, whereas reasoning does not have one testifying.

      • Charles said,

        November 27, 2012 at 1:47 pm

        That sounds reasonable, though I might add that what is known clearly by natural reason is also firm and certain. Our knowledge proceeds from unclear or fuzzy generalizations which are nevertheless certain to a more clear and articulated knowledge of the same that shares in the certainty of the original concepts. The certitude of faith, however, is of a different order and is grounded in God’s authority, which cannot deceive. As the habit of understanding/intellectus/nous is to first principles in the natural order of knowledge, so is faith to the first principles of revealed truth.

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