What we finally came to in our last discussion was an idea (from Tom) that knowledge isn't an internal mental state -- rather, it is a kind of relationship between you and the thing you know about. There's a contemporary school of philosophy that believes just that; but it is also true of the ancient position.
As Aristotle explains in De Anima and elsewhere, knowledge comes to be in us via a process that starts when we encounter the unknown thing. First we must perceive the thing through our senses. Either the sense itself or (in cases where more than one sense is involved) our "common sense" will present us with an image of the thing in our minds. This image in our minds is very similar to what Kant was calling our representation, but for Aristotelians it is not knowledge. Knowledge comes after we use our imagination:
To the thinking soul images serve as if they were contents of perception (and when it asserts or denies them to be good or bad it avoids or pursues them).... The faculty of thinking then thinks the forms in the images, and as in the former case what is to be pursued or avoided is marked out for it, so where there is no sensation and it is engaged upon the images it is moved to pursuit or avoidance. E.g.. perceiving by sense that the beacon is fire, it recognizes in virtue of the general faculty of sense that it signifies an enemy, because it sees it moving; but sometimes by means of the images or thoughts which are within the soul, just as if it were seeing, it calculates and deliberates what is to come by reference to what is present; and when it makes a pronouncement, as in the case of sensation it pronounces the object to be pleasant or painful, in this case it avoids or persues and so generally in cases of action.In other words, we take our initial image and use our imagination to add or subtract qualities. In this process, we sort out what it is that makes the thing that kind of thing -- the purpose, or function, which Aristotle calls the 'final cause.' The beacon can be lit or not; and in sorting out the difference we learn what it is that makes it a beacon and not just a fire (i.e., that it is lit only when the enemy is coming; and thus its final cause is to warn us of invasions). A chair can have two legs or three or four; or it can be blue or red. None of these things causes it to stop being a chair. However, if it is too small, or broken, it cannot be a chair (though it might, in the first case, be a toy chair). A bird can be bigger or smaller (and even flightless!), but it serves a purpose (its own purpose, that is: it sustains itself as a bird, and is involved in the production of more birds of that type).
At this point, we have knowledge. In Aristotle's terms, the final cause is normally also the formal cause -- that it, it is the form of the thing. The form of the chair or the bird comes to be in our minds. That is real knowledge, without mistake: we possess the form.
There are a couple of problems with this approach. It will jump out that Aristotle is using at least one and possibly two invisibles of the type that the West has come to fear since Ockham. "Form" isn't visible except when expressed in matter; the form in our minds is visible only as an image in our minds. Likewise, Aristotle puts all this down to the working of the soul. It seems like we could simply say that he's using "soul" where we would use "mind," but that's not right: the soul turns out to be another form. In fact it is our form, the organizing principle that makes us who we are and gives us our purpose (which, for Aristotle, is to seek understanding through rational activity; but you can take the more pedestrian view that our purpose, as with any animal, is merely to sustain ourselves and produce others like us).
The other problem is that Aristotle has a difficulty with how the form could come to be in our minds. In the Physics, he gives an account in which any sort of motion is a movement of a thing from potential to actual (or a falling away: a house can move away from being a house by collapsing, so that it is again only a potential house).
So if the form comes to be in our minds, it must have already existed there potentially. That's a very interesting claim, but it is a claim that makes sense of the idea that there is a relationship between us and the world. It's a much brighter picture than that which comes from Kant, because we really have knowledge -- the actual form of the actual things -- and it makes sense that we can convey that knowledge to others.
But then you realize that this means that all forms must exist in our minds potentially -- how could that be the case? (The claim is not as shocking as it sounds at first: if you think it through, you realize that it really must be true that, if we can have knowledge of X today, we must have had the potential to know X yesterday. Thus, it follows that you now potentially know everything that you could actually know.) It makes a kind of sense on something like an externalist picture: we are part of the world, not separate from it, and thus we are related to the world in certain ways. One of those ways could be having a mind shaped for knowledge of the world.
There is another problem, though, which is that we can also obtain knowledge through contemplation alone: for example, we can come to knowledge of mathematical truths simply by thinking. We are never encountering an actual form in an actual thing; yet we are coming to knowledge all the same. That means not only that we must have the potential for the knowledge in our minds, but that we need an account of where the actual form is that we are grasping.
Aristotle's solution is to posit an "Active Intellect," which is to say a kind of universal consciousness in which all human minds participate. This is a surprising solution, very much unlike Aristotle -- it's almost Platonic, and very similar to what the later neoplatonists will suggest. This Active Intellect contains all the forms in an actual way, and thus this explains how our minds can obtain knowledge through contemplation alone.
The modern urge is to do away with "forms" as invisible or mystical, but remember what forms are: they're organizing principles that structure matter in a particular way. These things certainly exist: this is what DNA does, for example; or, if you like, the difference between hydrogen and helium is the way in which its matter is ordered and structured. So forms are real enough; and they do exist in an actual way, and come to be in our minds when we grasp them.
Here the problem is the opposite one we had before. There are large parts of this picture that really work, and are highly satisfying; but there remain some troubles we have to sort out. Let's stop here and talk it through.