In his own life, Kant was mostly a spectator and critical thinker. His critical thinking was a solitary business, but it was not cut off from those from whom he expected inputs. His critical thinking and analysis was based on the presumption that that those who directly participate in events are willing and able to render an account of what they experience and think.
In her lectures on Kant's political philosophy (Hannah Arendt: Lectures on Kant’s Political Philosophy, Edited by: Ronald Beiner), Hannah Arendt offers a brief outlook on the role of the spectator in Kantian thought. In Lecture 7, she talks about Kant’s spectator lifestyle: “Kant introduced and taught a course in physical geography at the university. He was also an eager reader of all sorts of travel reports, and he—who never left Konigsberg—knew his way around in both London and Italy; he said he had no time to travel precisely because he wanted to know so much about so many countries.”
In Lecture 8, Arendt notes that for Kant the importance of an event lay “exclusively in the eye of the beholder, in the opinion of the onlookers who proclaim their attitude in public.”
In Lecture 9, Arendt talks about the Kantian position of the onlooker: “What he saw counted most; he could discover a meaning in the course taken by events, a meaning that the actors ignored; and the existential ground for his insight was his disinterestedness, his nonparticipation, his noninvolvement. The onlooker's disinterested concern characterized the French Revolution as a great event.”