Task: Text Categorization
Input (English): This thinker observed that "every action can only take place in consequence of a sufficient motive" in The Basis of Morality, and also wrote an essay arguing that the title group of people can't take a "purely objective interest in anything", titled "On Women". This philosopher applied "observations of unbiased physical investigators" to the "kernel of [his] Metaphysics" in On the Will in Nature, and described four classes of objects in On the (*) Fourfold Root of the Principle of Sufficient Reason. The "Epistemology" volume of his best known work discusses the Kantian "thing-in- itself". For ten points, name this pessimistic German author of The World as Will and Representation.
Output (English): Social Science