Abstract Kant's account of extraterrestrials in The Universal Natural History exposes a contradiction in his thought between conceiving of human beings as essentially disembodied spirits and conceiving of human beings as essentially embodied spirits. This contradiction also divides Kant's accounts of the possibility of human perfectibility: religion provides hope but goes against reason, while history satisfies reason but condemns humans to despair of progress.
Hank Southgate (2025) studied this question.