On the Fourfold Root of the Principle of Sufficient Reason

Schopenhauer's doctoral dissertation, wherein he elaborates upon the Principle of Sufficient Reason first expounded in ancient Greek philosophy, is published here complete.

The Principle of Sufficient Reason posits that everything that ever happens has a reason or root cause. It is by drawing both upon the principle's ancient origins, and basing his theory upon Immanuel Kant's theory of knowledge, that Schopenhauer - in his own view - completed the epistemological parts of Kantian thought left undone or insufficiently concluded.

Although Schopenhauer expanded his philosophical theories as he matured, he would frequently refer his readers and students back to this original dissertation as a starting point. Over time however, On the Fourfold Root has faded into relative obscurity, with Schopenhauer's later, lengthier works eclipsing its significance.

The four classes of reason are as follows:

Becoming; over time, an object gains time and space and is thus able to be perceived, interpreted, evaluated and judged.

Knowing; all past judgments, together with conceptions established via the use of reason, make up the basis of the known.

Being; separated into two categories; firstly time is explained as an inner sense, pertaining to the temporal and secondly, space pertains to the spatial occupancy of the subject.

Willing; the perceiving, knowing, subject may be able to perceive itself as a force of will - however this process takes action, and time, to establish itself.

The translation to English, by German author Karl Hillebrand, is the classic. This edition is based upon the fourth edition, which was originally published in 1903.