Full Idea
Considered objectively, there can only be one human reason, there cannot be many philosophies; in other words, there can only be one true philosophy from principles, in however many conflicting ways men have philosophised about the same proposition.
Gist of Idea
Because there is only one human reason, there can only be one true philosophy from principles
Source
Immanuel Kant (Metaphysics of Morals I: Doctrine of Right [1797], Pref)
Book Reference
Kant,Immanuel: 'The Metaphysics of Morals', ed/tr. Gregor,Mary [CUP 1991], p.36
A Reaction
An idea that embodies the Enlightenment ideal. I like the idea that there is one true philosophy, because there is only one world. Kant is talking of philosophy 'from principles', which means his transendental idealism.