Descartes, Spinoza, and Leibniz: Continental Rationalism

Overview of Rationalism and Empiricism

Continental rationalism argues essentially that the ultimate source of knowledge can be found within human reason. Further, it argues that truth can be deduced from our innate ideas, and mathematical proof ultimately became the model for rationalist investigation. This philosophical movement began in the 17th century with the work of René Descartes and spread through continental Europe during the 17th and 18th centuries. Many philosophers who adopted Descartes' theories, or incorporated his ideas into Calvinist theology, were termed Cartesians. In contrast, Benedict Spinoza and Gottfried Wilhelm Leibniz each adopted Descartes' ideas and developed their own views within his overarching theme of human reason as the ultimate source of knowledge (The Internet Encyclopedia of Philosophy; Solomon).

The primary philosophical rival to Continental rationalism was British empiricism. Commonly seen as founded by philosopher John Locke, British empiricism argues that knowledge comes through the senses or experience, and that problems should be investigated through the inductive method developed by Francis Bacon (The Internet Encyclopedia of Philosophy). Empiricists disagree with rationalists who believe that reason is itself a source of knowledge, and they seek to explain what rationalists attribute to reason in terms of experience. Often, empiricists regard skepticism as the best alternative to rationalism (Stanford Encyclopedia of Philosophy).

Interestingly, the traditional distinction between empiricism and rationalism has been challenged in recent years. Contemporary historians like Louis Loeb argue that the content of the metaphysical and epistemological positions of specific philosophers should take precedence over their specific adherence to either the empiricist or rationalist camp (The Internet Encyclopedia of Philosophy).

Descartes, Spinoza, and Leibniz

Descartes, Spinoza, and Leibniz have often been grouped together as representing the school of Continental rationalism (The Internet Encyclopedia of Philosophy). While the works of these three philosophers contain significant differences, the commonalities in their thought clearly identify them as Continental rationalists. Especially significant are their common adherence to Leibniz's principle of sufficient reason and the shared conviction that the fundamental nature of the universe can only be known through a priori reasoning.

Any discussion of Continental rationalism must begin with René Descartes' Meditations on First Philosophy, often considered the seminal work of this philosophical tradition. First published in 1641, the Meditations consists of six separate meditations. Descartes begins by assuming that all of his prior beliefs were derived from either poor logic or misleading information, and he attempts to discard any belief that is not completely certain. In the end, he asserts that the only thing he cannot doubt is his own existence. This realization gave rise to his famous declaration, cogito ergo sum — "I think, therefore I am." As Descartes himself wrote, he had "convinced myself that there is absolutely nothing in the world, no sky, no earth, no minds, no bodies. Does it follow that I too do not exist? No: if I convinced myself of something then I certainly existed." From this foundation, he proceeds to establish what else can be known with certainty.

In Discourse on Metaphysics, Gottfried Wilhelm Leibniz provides a concise overview of his thoughts on metaphysics. He argues that all human knowledge is analytic in nature and a posteriori, and that all human knowledge ultimately comes from God, who "is an absolutely perfect being" (p. 3). For Leibniz, God possessed "supreme and infinite wisdom" (p. 3) and acted "in the most perfect manner not only metaphysically, but also from the moral standpoint" (p. 3). For God, however, all truths are analytic a priori.

Benedict Spinoza's work The Ethics; Treatise on the Emendation of the Intellect argues that an understanding of knowledge ultimately arises from a metaphysics in which God and nature are deeply intertwined. Spinoza does not see God as simply the all-powerful creator of the universe, but as nature itself. He argued that God and nature are essentially the same underlying reality of the universe. Nature contains an almost infinite number of attributes, including the physical and mental worlds, which were thought not to interact with each other. Nature, in turn, is a complete system that encompasses the acts and thoughts of humans. Humans can only achieve happiness if they understand this system and their place within it.

While this discussion illustrates some of the differences among the philosophies of Descartes, Spinoza, and Leibniz, these three philosophers are commonly and accurately grouped together as representing Continental rationalism. Each shares the foundational idea, first articulated by Descartes, that human reason is the ultimate source of knowledge.

Conclusion

Descartes, Spinoza, and Leibniz shared a commonality of philosophical thought that accurately identifies them as three of the main figures of Continental rationalism. Although the three philosophers differed in many of their specific ideas, they all adhered to the core beliefs that characterize Continental rationalism: that reason is the ultimate source of knowledge, that all events can be understood through the principle of sufficient reason, and that knowledge must proceed from self-evident, a priori truths. Taken together, these three philosophers helped to formulate a philosophy of metaphysics that had a lasting and profound impact on Western civilization.

Works Cited

Descartes, Rene. Descartes: Meditations on First Philosophy. Prentice Hall, 1960.

Hauptli, Bruce W. Continental Rationalism Characterized. [University], 2003. 08 November 2004.

Liebniz, Gottfried Wilhelm. Discourse on Metaphysics and the Monadology. Prometheus Books, 1992.

Solomon, Robert C. Continental Philosophy Since 1750: The Rise and Fall of the Self (History of Western Philosophy, No. 7). Oxford University Press, 1988.

Spinoza, Benedictus De. The Ethics; Treatise on the Emendation of the Intellect; Selected Letters. Hackett Publishing Company, 1991.

Stanford Encyclopedia of Philosophy. Rationalism vs. Empiricism. 08 November 2004. http://plato.stanford.edu/entries/rationalism-empiricism/#1.1

The Internet Encyclopedia of Philosophy. 2001. Continental Rationalism.