This is jewel. You can use a taxi driver to get to the airport (that's a means), but you cannot treat them merely as a tool. You must respect their rational autonomy. Similarly, you cannot use yourself (by committing suicide out of despair) because your own humanity has dignity, not a price.
identified two main filters:
To understand Kant is to understand the "Copernican Revolution" of the mind. Before Kant, philosophers debated whether the world imprinted itself upon our minds like a seal on wax. Kant argued the reverse: our minds impose structure upon the world. His work is dense, his terminology notorious, and his arguments complex, but the rewards of engaging with his philosophy are insights that forever alter how one perceives reality, ethics, and beauty. This is jewel
drew a line between two realms:
This distinction is the death knell for traditional rationalist metaphysics. When reason attempts to use the categories beyond the bounds of possible experience (e.g., asking for the absolute beginning of the world in time, or for the existence of a necessary being), it falls into and antinomies —equally valid but contradictory conclusions. Kant thus “denies knowledge to make room for faith.” While theoretical reason cannot prove God, freedom, or immortality, practical reason (morality) can postulate them as necessary conditions of the moral law. Similarly, you cannot use yourself (by committing suicide
Why? Because argued that the human mind comes with pre-loaded "filters." Think of it like wearing blue-tinted glasses: you will never see the world’s true colors, only blue-shades. Your glasses are not a flaw; they are the condition for seeing anything at all. Kant argued the reverse: our minds impose structure