This philosopher insisted that enjoyment is subjective in Observations on the Feeling of the Beautiful and Sublime. He proposed an early version of democratic peace theory in his essay, "Perpetual Peace." He described the title concept as "man's emergence from his self-imposed immaturity" in "What Is Enlightenment?" He was the first philosopher to delineate the difference between analytic and synthetic propositions, and in his Groundwork of the Metaphysics of Morals, he 
This philosopher insisted that enjoyment is subjective in Observations on the Feeling of the Beautiful and Sublime. He proposed an early version of democratic peace theory in his essay, "Perpetual Peace." He described the title concept as "man's emergence from his self-imposed immaturity" in "What Is Enlightenment?" He was the first philosopher to delineate the difference between analytic and synthetic propositions, and in his Groundwork of the Metaphysics of Morals, he introduced the concept of the categorical imperative. For 10 points, name this author of the Critique of Pure Reason.
This philosopher insisted that enjoyment is subjective in Observations on the Feeling of the Beautiful and Sublime.
Immanuel Kant