Ethics, Demonstrated in Geometrical Order

Spinoza's central claim is that God and Nature are one and the same substance—Deus sive Natura—and that all things follow from this substance with absolute necessity. He rejects the Cartesian dualism of mind and body, the notion of a transcendent creator God who acts with purposes, and the idea of free will as a power of absolute choice. For Spinoza, humans are modes of Nature, determined by causes just as everything else is; freedom consists in understanding this necessity and acting from adequate ideas rather than passive emotions.

The Ethics introduces conatus—the striving of each thing to persevere in its being—as the actual essence of every finite mode. In humans, conatus manifests as desire, and the ethical project consists in transforming passive emotions (those caused by external things) into active emotions arising from one's own power. This framework has been used in contemporary international relations theory to conceive of states as composite bodies that affect and are affected by one another, grounded in a physicalist reading of Spinoza's political thought.

Spinoza chose the geometrical method—definitions, axioms, propositions, demonstrations—because he believed mathematics provided the model for certain knowledge, and because the form itself compels the reader to follow the reasoning rather than merely accept conclusions. Critics have long complained that the method imposes an artificial order and is 'embarrassing, laborious, obscure' on first reading. Defenders note that the cross-referencing system allows readers to trace exactly which prior propositions justify any given claim, creating a remarkably interconnected network of arguments.

The Ethics was published in 1677, shortly after Spinoza's death, and was immediately condemned as atheistic. Pierre Bayle denounced its central identity of God and Nature as a 'monstrous hypothesis.' Over the following century, however, its reputation transformed. German Romantics like Novalis celebrated Spinoza as 'God-intoxicated,' and later philosophers from Hegel to Deleuze claimed him as a precursor. Today the Ethics is recognized as one of the most important works of early modern philosophy, though interpreters remain divided on whether Spinoza was an atheist, a deist, or a mystic.

Spinoza's direct remarks on interstate relations are sparse, confined mainly to a few paragraphs of the Political Treatise. However, scholars have argued that his physicalist framework—treating states as composite bodies that strive to persevere and are affected by other bodies—provides resources for IR theory. Hersch Lauterpacht noted that Spinoza's separation of morals from politics and his identification of power with right became part of the intellectual currents that shaped international law. More recently, scholars have used Spinoza to challenge the Hobbesian analogy between individual and state in the international state of nature.