Book

On the Fourfold Root of the Principle of Sufficient Reason

by Arthur Schopenhauer

Summary

This treatise establishes the Principle of Sufficient Reason as having a "Fourfold Root," meaning one underlying reason that presents itself under four distinct aspects, rather than four separate reasons for a judgment. Schopenhauer argues that all our representations stand in a regulated connection, which the Principle of Sufficient Reason expresses generally, but which assumes different forms based on the four distinct classes into which everything that can become an object for us can be divided.

The book follows a method based on Plato and Kant's laws of homogeneity (grouping things by resemblance) and specification (not reducing distinctions). By applying these laws to the relations that ground the Principle of Sufficient Reason, these relations separate into four species, each corresponding to a class of objects for the subject, and each exhibiting a different form of the Principle of Sufficient Reason.

Key concepts

  • Fourfold Root of the Principle of Sufficient ReasonThe idea that a single underlying reason manifests in four distinct aspects, corresponding to four classes of objects.
  • Law of HomogeneityThe principle of grouping things together into kinds, then kinds into species, and so on, by observing resemblances.
  • Law of SpecificationThe principle of not arbitrarily reducing the distinctions between entities.
  • RepresentationsAll things that can become an object for the subject, which are understood as existing in a regulated connection.
  • Classes of Objects for the SubjectThe four categories into which all representations are divided, each corresponding to a specific form of the Principle of Sufficient Reason.

From the book

"Your answers (to the objection in question) are not the right ones. Here there cannot yet be a question of the thing in itself, and the
[8] See "Die Welt a. W. u. V.," vol. ii. pp. 17-21, and vol. i. p. 39 of the second edition. (The passages referred to by Schopenhauer
W. u. V., vol. i. p. 22 _et seqq._, and vol. ii. chap. ii. of the second edition; vol. i. p. 22, § 6, and vol. ii. chap. ii. of the third edition. [10] The passage I have quoted above from Schopenhauer's letter is

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