The knowability of reality
Kant has two ironic observations that fix his theory firmly in the domain of philosophical mystery. The first is that reality is knowable, and the second is the opposite. Firstly, Kant gives credit to the Rationalists and the Empiricists, showing that since reality is knowable and since humans seem to be able to understand a considerable amount about reality through science, there is an impetus put science in a place of authority. The irony is famous but nuanced; why should there be a reality that is so discernible to humans? Although the knowability of the universe might seem to be comforting, it raises more philosophical questions than it answers.
The unknowability of the universe
Then, on the flip side, Kant observes that for all the scientific genius of human history, the truth is that the universe is strangely unobservable in many regards. Past the precipice of human observation, there is a vast, vast reality that we can trust exists, but cannot observe. The limits of human consciousness are also to be considered. This paradox adds humility to Kant's answer, because at the end of the day, humans are only qualified to discuss what exists within their frame of reference, which is actually not all that much in the grand scheme of the universe. We can't observe the past directly, or the future, or the whole scope of the universe, or dark matter (we now know), and so on.
Morality and metaphysics
Kant's primary argument for morality and ethics is that there seems to be an implicit metaphysic that is presupposed by religions and moral codes that could be discerned and understood more completely through rigorous analysis. This is ironic, because it is applying science to the prospects of religion, but more importantly, morality seems to be something subjective and spontaneous, and yet, Kant suggests that morality is built into the fabric of reality in some mysterious way.
The hierarchy of goodness
Kant's metaphysical view of morality leads to an integral/differential view of goodness, so that goodness is ranked in a hierarchy. He gives examples of how various maxims of goodness can be set against one another, leading to conundrums. These conundrums are often ironic in nature, and Kant solves them like riddles by showing certain moral imperatives to be greater or less than others. For instance, permanent damage is obviously a greater risk than temporary damage that recovers.
Language and data
Kant discusses the way language shapes data from the human psyche in various ways. He is especially concerned with how language can be used more precisely, showing various kinds of language: analysis, synthesis, empirical observation, and others. The goal is to clarify language to its mathematical, logical content so that the meaning can be calculable. The irony is that language can have such nuance; a true thing must be stated precisely or else ambiguity and subjectivity can infect the data and stain the truth with bias.
