---
tag: RC0MK948CQ
kind: statement
role: proposition
name: Four Laws
sources:
  - wikipedia: en:1252308@r1357791526
    locator: Law of thought, section History > Four Laws
    note: adopted
    mention: wikipedia://en/1252308#F6BO
    sections: [Statement]
inventory: [9SYXAS9NH4]
---

## Statement

Several authors have added the principle of sufficient reason as the fourth "law of thought". William Hamilton and Arthur Schopenhauer were among them. Schopenhauer later believed the law of excluded middle and the principle of sufficient reason were the two laws of thought.