Plato held that the Form of the Good makes other Forms intelligible to us in a way comparable to how the sun makes physical objects visible to us. He also took our knowledge of the Forms to be inexplicable in empirical terms, since the Forms have a necessity, eternity, and perfection that the objects of the senses lack. His solution was to regard knowledge of the Forms as a kind of recollection of a direct access the soul had to them prior to its entrapment in the body.
St. Augustine inherited this Platonic picture and transformed it. The Form of the Good becomes God; the other Forms become ideas in the divine intellect; and recollection is replaced by divine illumination of the human mind. The general idea and motivation of Augustine’s doctrine of divine illumination is clear enough, at least in light of its Platonic background. But nailing down it precise content is notoriously difficult.
The Platonic background
How was the Form of the Good supposed to make the other Forms intelligible, on Plato’s account? Here’s one way to think about it. A Form is a standard of perfection. A particular triangle is a better or worse specimen of triangularity the more or less perfectly it participates in the Form of Triangle. For instance, a triangle drawn slowly and carefully using a ruler is a better specimen than one drawn hastily and sloppily, because it more perfectly approximates the standard that is the Form. Something similar can be said of all other things and their degrees of approximation to the standards that are the Forms they participate in.
Now, to understand the Form of X (whatever X is) as the standard by reference to which a particular X is a good X is essentially to see the Form as itself an instance of goodness – as participating in the Form of the Good. In this way the Form of the Good illuminates – it makes intelligible to the eye of the intellect – the other Forms.
But for Plato, you’re not going to get knowledge of the Form of the Good from acquaintance from particular good things, any more than you’re going to arrive at knowledge of the Form of Triangle from particular triangles. And thus you’re not going to get it from sensory experience, which can only ever get you acquainted with particulars. So our knowledge of the Forms must be a kind of drawing out of what was already in us prior to experience. And since it can only have gotten in us by some sort of contact with the Forms, and we haven’t had such contact in this life, we must have had such contact prior to this life. Knowledge of the Forms is thus a remembering of this prior contact.
The Augustinian transformation
The skeptical reader might wonder whether Augustine’s alteration of Plato’s general picture is motivated merely by Christian theological concerns, with no independent philosophical rationale. But that is not the case. For one thing, during the long history of the Platonic tradition between Plato and Augustine, God had, for philosophical reasons, already long since displaced the Form of the Good as the first principle of all things (even if Augustine’s view of the divine nature differed in important respects from that of predecessors like Plotinus).
More to the present point, potential theological problems with the notion of the pre-existence of the soul were not the reason Augustine rejected the theory of recollection. The reason had rather to do with inadequacies in that theory as an account of our knowledge of the Forms. As Peter King notes (in his article on Augustine’s epistemology in the of The Cambridge Companion to Augustine), Augustine was keen to emphasize the objectivity of our knowledge of eternal truths of a mathematical sort, and of the Forms in general. When you and I grasp that 2 + 2 = 4, it is one and the same truth that we both intersubjectively grasp, just as it is one and the same table we are looking at when we both see the table before us. Similarly, when you and I contemplate the Form of Triangle, it is one and the same objective reality that we both contemplate. But the most one could be aware of via memory is a subjective mental representation of a Form, not the Form itself. Hence, recollection of a purported acquaintance with the Forms prior to birth cannot explain how we intersubjectively know them now.
Something going on now must account for that. King points out that for Augustine, we also need to account for the way that here and now you can come to understand such eternal truths, in a flash of insight or moment when it “clicks” (as when you figure out a proof or otherwise grasp the connections of logical necessity between propositions). Mere recollection of something you purportedly learned prior to your soul’s incarnation in the body cannot account for that. The theory of illumination is meant to explain all of this.
The basic idea
Recall that for Augustine, the Forms are to be understood as ideas in the divine intellect. Indeed, their necessity, eternity, and perfection provide the basis of an argument for the existence of a divine mind to ground them. (I develop a modernized version of the Augustinian argument for God’s existence in chapter 3 of .)
How, then, can we know the Forms? For example, how could we know the Form of Triangle from experience of particular individual triangles? For any such triangle is neither necessary nor eternal, but comes into being and passes away. It is also imperfect, lacking the perfect straightness of sides that a triangle is supposed to have given its essence. And any sensory representations or mental images we can form of a triangle are going to have the same defects. Whatever else we can know of a triangle through sensation and imagination, the necessity, eternity, and perfection of the Form it participates in cannot be known that way.
Now, compare such a triangle to a red object sitting in a dark room, or to a red stained glass window on a moonless night. The redness is there in the object or the window, but you will not see it without light. You see the red of the object when light shines on it, and the red of the window when the light shines through it. Absent such light, the redness will be invisible, even if you can know other features of such objects (by touching them say). But the presence of the light immediately reveals the redness to the eye. You might even say: “Aha! It’s red!”
Similarly, Augustine holds, something analogous to light, but coming from God – in whom exists the Form of Triangle in all its necessity, eternity, and perfection – is what reveals these properties to the “eye” of the human intellect. You might even have a flash of understanding that yields an “Aha!”
The analogy between divine illumination and Plato’s comparison of the Form of the Good to the sun makes the general outlines of Augustine’s idea clear enough. But making out the details is difficult. Exactly what does this “illumination” amount to? Obviously it does not involve light of the ordinary sort. But what, then?
For starters, it is useful to keep in mind that we often describe the intellect as seeing that a proposition is true or that the conclusion of an argument follows from its premises. There is an analogy between what the eye does when it sees a physical object and what the intellect is doing. And it is not unreasonable to suppose that there might also be an analogy between the means by which the eye does what it does and the means by which the intellect does what it does. If the former sort of seeing requires light, so too might the latter sort of “seeing” require something analogous to light.
But by itself that doesn’t tell us much. The help provided by the analogy with Plato’s comparison of the Form of the Good to the sun is also limited. Yes, the divine intellect illuminates the Forms for our minds just as the Form of the Good was said to do. But the manner in which they do so is evidently different, at least given my proposed reading of how this works in the case of the Form of the Good. I suggested that we read Plato as holding that, just as a tree and a triangle participate in the Form of Tree and the Form of Triangle, respectively, those Forms in turn participate in the Form of the Good. And this makes those Forms intelligible, in the same way they make particular trees and triangles intelligible.
But seeing this involves (a) grasping the Form of the Good and (b) grasping the relation between the other Forms and it. That is to say, it involves mental acts precisely of the kind that Augustine is trying to explain. So, illumination of the kind he is appealing to is evidently different and more fundamental than the kind of which Plato was speaking (at least as I’m reading Plato). But then, what does it amount to if it isn’t quite what Plato was speaking of? The doctrine of illumination needs some illumination.
Over the centuries, there have been three main approaches to spelling out Augustine’s position in more detail. The first holds that in knowing the Forms, the human mind sees directly into God’s own mind. The way you grasp the necessity, eternity, and perfection of the Form of Triangle, for example, is by virtue of your mind’s ascending from acquaintance with mere particular individual triangles and becoming acquainted instead with the divine idea of triangularity. This interpretation is associated with the early modern philosopher Nicolas Malebranche, and is known as “ontologism.”
This interpretation would certainly make it clearer what illumination amounts to. But unfortunately, it is highly problematic both philosophically and theologically. The standard objection is that it would seem to imply that we have a direct intellectual grasp of God’s essence, which we clearly do not have. If we did, we would have complete beatitude and be unable to doubt God’s existence, neither of which is the case. It is also absurd to think that all people who are able to grasp even basic mathematical truths like 2 + 2 = 4 – which includes those who are utterly foolish and morally depraved no less than the wise and saintly – are thereby able directly to know God’s mind. (Certainly, Augustine would not have held such a thing.)
A second interpretation holds that “illumination” amounts merely to the fact that God conserves the human intellect in being and concurs with its operation (just as he conserves and concurs with everything else), where the intellect is that aspect of our nature that is uniquely God-like. This sort of interpretation is sometimes proposed by Thomists as a way of reconciling Augustine’s epistemology with Aquinas’s. But it is decidedly deflationary, reducing Augustine’s view to just a colorful but very imprecise way of saying what Aquinas would later say with more precision. Whereas the first interpretation makes the doctrine of illumination very interesting but highly problematic, the second makes it unproblematic but also uninteresting. It also just isn’t exegetically plausible as a reading of Augustine, who was thinking along Platonic rather than Aristotelian lines.
The correct interpretation is surely the third one, which is a middle ground between the first two. That is to say, it reads Augustine as making a stronger and more distinctive claim about the nature of illumination than the second interpretation does, but without going to the extreme of saying that the human mind can peer directly into the divine mind.
The basic idea of this third interpretation can be understood by returning to the analogy of the red object and stained glass that are illuminated by sunlight. When you see the redness of the illuminated object or the glass, it is the object and the glass that you are looking at, not the sun itself. The sun is not what you see, rather it is that by which you see. But it is nevertheless something distinct from you, and without the help of which your eye would be unable to detect the redness.
Similarly, light from the divine intellect is what illuminates the Forms for our intellects. This divine light is not itself what the intellect sees (contrary to the first, ontologistic interpretation of Augustine), but rather that by which the intellect sees. But still (and contrary to the second, Thomistic interpretation of Augustine), it is something distinct from any activity of the human intellect itself, and distinct from God’s conservation and concurrence with it. It is an extra divine assistance without which the intellect, relying merely on its own capacities, would be unable to grasp the necessity, eternity, and perfection of the Forms.
This is helpful, though more as a way of telling us what illumination does not involve rather than what it does involve. To be sure, it is clear that it involves a kind of divine causality over and above the conservation and concurrence with the human intellect considered just by itself. But exactly what is the nature of this causality?
Gareth Matthews (in his essay on Augustine’s epistemology in the first edition of the Cambridge Companion to Augustine) suggests a further interesting interpretive detail. As I discussed in a post from a few years ago, Augustine developed an early version of the view that material phenomena are by themselves inherently semantically indeterminate (a thesis much explored by contemporary analytic philosophers like Quine and Kripke). That is to say, given just the physical facts alone, there can be no fact of the matter about exactly what an utterance, gesture, or physical representation means. If you add to this the premise that there nevertheless sometimes is a fact of the matter about what they mean, it follows that there must be some additional factor over and above the physical facts.
Matthews suggests that dealing with this issue is another job that Augustine intends the doctrine of divine illumination to do. Hence, consider a triangle drawn in black outline on a marker board, and also all the physical facts involved in your seeing it and judging it to be a triangle (the causal relations between the marker board and your eyes, the brain activity going on as you look at and contemplate it, the utterances you make as you look at it, and so on). The semantic indeterminacy arguments developed by Augustine, Quine, Kripke, et al. show that these physical facts alone could not suffice to determine that you are conceptualizing what you are looking at as a triangle – as opposed, say, to conceptualizing it as a triangle with black outlines, specifically, or as a trilateral, or whatever.
And yet there is a fact of the matter about which of these is in reality the way you are conceptualizing it. Matthews’ suggestion is that divine illumination is at least part of the story about what makes this the case. You might think of it on the following analogy (mine rather than Matthews’). Suppose you are trying to get someone to see something in the distance, such as a certain constellation of stars. He says: “I don’t see it. Where?” You grab his head and move it slightly, directing or aiming it toward the specific area of the night sky you want him to see. Then he does. “Oh yes, now I see it!”
Matthews seems to be suggesting that divine illumination is analogous to that. The physical facts, even together with the facts about your own immaterial intellect, are not sufficient to determine that you will conceptualize what you see as a triangle, rather than as a triangle with black outlines, specifically, or as a trilateral. But the divine intellect “grabs” your intellect, as it were, and directs or aims it in such a way that at that moment you conceptualize it the first way rather than the other ways.
Naturally, this raises all sorts of further questions. But it does seem to illuminate a little further the nature of the causality Augustine attributes to divine illumination.