Conversation so far:
What was Kant's political philosophy?
listed several conditions that he thought necessary for ending wars and creating a lasting peace.
They included a world of constitutional republics.
What were the conditions?
His classical republican theory was extended in the Science of Right, the first part of the Metaphysics of Morals (1797).
What else did he believe?
Kant believed that universal history leads to the ultimate world of republican states at peace, but his theory was not pragmatic.

Question: Were his beliefs controversial?
Self-contained rewrite: Were Immanuel Kant’s political philosophy beliefs considered controversial?