So, Kant basically ascribed to the mind a real creative power – things are understandable only insofar as they brought under or within the conditions of sensibility. This I’ll call the active power of the mind, since the categories for understand-ability are supplied by the mind. Now, as I said before, that the mind is in fact an active and not merely passive factor in our knowledge of the world is a fairly incontestable point, but thinking more on this topic led me to think about the intellect in general.
Aristotle held that the intellect was divided into the active (a) an the passive (p). p is the part of the intellect which receives data from the material world, while a acts as a kind of formal cause on the sensory data, forming ideas and thoughts with determinate structure. Aquinas basically held this same view, but tweaked it a bit: p still receives sensory data, but a grasps the form, which it abstracts, from the sensory data (Scotus disagreed with this and believed that the object of the intellect wasn’t the essence or quiddity of a thing, but being itself, but for right now I won’t go into that – for a bit more on that topic, see this post). So you basically have a concept of the intellect (and there’s a lot more to it, with categories like quality and whatnot, but this suffices for present purposes) where it is both passive and active in its knowledge of the world.
The medievals had this great concept: the fit of the intellect to reality. There is some kind of match between the intellect and reality, or the world or whatever you like to call it. Our cognitive faculties are able to allows us to know things about the world – of course, the medievals attributed this to the fact that God had created the world in this way (which I also happen to believe), but whether or not one believes that such a fit is a product of divine creation, it certainly seems that there is in fact a fit between our intellect, or our cognitive faculties and the world in which we live.
This brings me from the medievals ( in my mind, all roads in philosophy lead to the medievals) back to Kant. Where Kant made the mind purely active, the medievals, and the classical tradition as a whole, saw the mind as both active and passive – passive in that there is a world which acts upon our minds, and active in that in some way, the mind acts as a formal cause upon the sensory data received by the mind to impose a determinate form upon the data, either by abstracting the form or essence from the data or by some other means.