Immanuel Kant (1724-1804) argued that the phenomenal world we experience – the world of space and time with unified objects that are causally related – is the outcome of our minds giving form to sense data. Or, to use his terminology, our “categories of the understanding” giving form “intuitions.” To scientifically knowanything about the world we require a transaction between sense data and the categories of the understanding. There is no knowledge if we (a) have just mental forms without sense content or (b) just sense data without mental forms. This transactional model implies we never know anything about the world independent of the formative power of our minds, that is, we never come to know anything about the “thing in itself.” We only know what we create.
This theory of knowledge implies that, on the one hand, efforts by rationalists such as Descartes and Leibniz to argue for existence of the soul, the existence of God, and so on just using logic and ideas fail since they apply the categories to ideas without including sense data and, on the other hand, efforts by empiricists such as Hume and Locke fail as well since they think they can reduce knowledge to sense data alone.
But this account appears to run into a two-fold problem:
(1) How can we know anything about our mind if it itself is not a product of both sense data and the categories of the understanding?
(2) How can we know anything at all about the thing in itself, including that it is unknowable, if it is also not a product of both the categories of the understanding and sense data?
We can put it this way: both mind and the thing in itself are presuppositions for the transactional model of knowledge to make sense; so they themselves can’t be outcomes of that model. It appears that the conditions for the possibility of knowledge are not themselves conditions that can be known.
So we have a dilemma: if we don’t have knowledge of the mind and the thing in itself then the very framework of Kant’s analysis seems to fall apart; but if we do have knowledge of both then his theory of knowledge is false or certainly not comprehensive enough.
Now we might try and break out of this dilemma by challenging Kant’s account of scientific knowledge itself. Obviously in most cases we think knowledge will entail both a conceptual component and an empirical one. But I would argue we have plenty of knowledge about mathematical objects that can’t come with any sensible intuitions at all: we can think, and apparently know, a lot about figures with thousands of sides and we can think and utilize vast numbers like 1000 to the 10000000th power. And mathematics is obviously integral to science. Moreover, there is a general problem. Kant grounds necessity and objectivity in our species and its shared categories of the understanding giving form to sense data in the same way. But this means that necessity and objectivity are contingent on us: if we weren’t here as a species then all this necessity and objectivity would disappear. Basically, he is offering us a contingent necessity and dependent objectivity. For some, this may be enough to overcome the challenges of relativism. But for me, I prefer to pursue a more robust source of necessity and a conception of objectivity as that which is independent of us (for more on this, see the link below to my post on necessary truth). Plato, for example, offers us just this with his vision of eternal and immaterial Forms that would exist even if we did not and which are necessarily existing entities. And for many who are sympathetic to the Forms, the best way to make a case for them is to appeal to the necessity and objectivity of mathematical entities that we can think not experience with our five senses.
But for now let’s leave Kant’s account of science in place and ask: is this scientific mode of knowing the only way to know something? Kant’s word for his form of scientific knowledge is wissenschaft. But is scientific knowledge the only kind of knowledge there is? Well, Kant himself, in his Critique of Practical Reason, argues that we can turn to practical reason to understand ourselves as free beings that can engage in moral action. Indeed, we can only make rational sense of our moral lives by presupposing such noumenal freedom that would, of course, be radically different from the determinism (Kant’s Newtonian worldview was deterministic) that marks the phenomenal realm. Moreover, in his Critique of Judgment Kant claims that, in experiences of the sublime, our reason, which is that faculty for thinking things in a systematic nature and as a totality, can come to think infinity as a whole or a totality to which nothing else can be added. This thought allows us to have an uplifting aesthetic experience in which we feel we are not confined to the limits of our finite bodies. Without this ability to think infinity as a whole we wouldn’t have an experience of the sublime at all: it is a presupposition, like free will is a presupposition, that helps make sense of our experience.
Now, our experiences of moral action and aesthetic feeling are not scientific knowledge for Kant. But he does a masterful job in exploring how indispensable they are to understanding our experience as rational beings with moral and aesthetic capacities. Why not say they can, in some cases at least, offer us genuine forms of knowing? If they do offer us knowledge of some kind then perhaps we can, through certain kinds of feeling and action, come to know enough about the mind and the thing in itself in ways that would allow us to escape the dilemma that sticking with Kant’s theory of scientific knowledge places upon us.