Critique of the Kantian philosophy
"Critique of the Kantian philosophy" is a criticism Arthur Schopenhauer appended to the first volume of his "The World as Will and Representation" (1818). He wanted to show Immanuel Kant's errors so that Kant's merits would be appreciated and his achievements furthered.
Critique of Pure Reason
Kant decided to find an answer and spent at least twelve years thinking about the subject. Although the "Critique of Pure Reason" was set down in written form in just four to five months, while Kant was also lecturing and teaching, the work is a summation of the development of Kant's philosophy throughout that twelve-year period.