36. - Common Notions

Summary

Spinoza introduces common notions (notiones communes) in Part 2 of the Ethics in a short block of three propositions followed by two long scholia (E2p38–40s1,2). A central addition to Spinoza’s mature theory of knowledge, common notions are absent in the early TIE and KV but play an important role in the Ethics and the TTP. Common notions form “the foundations our reasoning” (E2p40s1) and the “foundations of philosophy” (III/179). While they clearly are central to his theory of knowledge, a considerable amount of conjecture is still required to reconstruct the finer details of Spinoza’s doctrine of common notions since he “set these aside for another Treatise” and therefore “decided to pass over them” in the Ethics. In that never written treatise, it seems, Spinoza intended to explain in more detail the use, clarity, and foundations of common notions, and their exact relation to axioms and the higher-order notions traditionally called “second notions” (E2p40s1, II/120).