Continental rationalists and their philosophical contributions

Descartes, Spinoza, and Leibniz are often accurately portrayed as the key figures representing the Continental rationalism. Continental rationalism is characterized by a belief that truth can be deduced from human reason, and that certain innate, or self-evident ideas form the basis for such knowledge. In contrast, British empiricism saw the source of knowledge could be found in experience and through the senses. While the works of Descartes, Spinoza, and Leibniz contain significant differences, they share the common beliefs in: 1) reason as the ultimate source of knowledge, 2) Leibniz' principle of sufficient reason, and 3) the idea that knowledge must come from self-evident, a priori truths. The belief in innate principles or ideas characterized the work of Descartes, Spinoza, and Leibniz, and is probably best characterized through their shared belief in the idea of a deity.

Overview of Rationalism and Empiricism

Continental rationalism argues essentially that the ultimate source of knowledge can be found within human reason. Further, Continental rationalism 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 the philosopher Rene Descartes, and spread through continental Europe during the 17th and 18th centuries. Many of the philosophers who adopted Descartes' theories, or incorporated his ideas into Calvinistic theology, were termed as Cartesians. In contrast, a number of philosophers like Benedict Spinoza, and Gottfried Willhelm Leibniz adopted Descartes' ideas, and developed their own views within Descartes' overarching theme of human reason as ultimate source of knowledge (The Internet Encyclopedia of Philosophy; Solomon).

The primary philosophical rival to Continental rationalism was British empiricism. Thomas Reid's Inquiry Concerning the Human Mind marked the beginning of British empiricism, commonly seen as founded by philosopher John Locke. This philosophical system argues that knowledge comes through the senses or experience, and further argues that problem should be investigated through the inductive method developed by Britain Francis Bacon (The Internet Encyclopedia of Philosophy). Empiricists disagree with the rationalists, who believed that reason is a source of knowledge, and seek to explain the information that rationalists give in terms of experience. Often, empiricists will see 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 empiricists 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 thought of Continental rationalism (The Internet Encyclopedia of Philosophy). While the works of these three philosophers do contain significant differences, the commonalities in thought clearly identify Descartes, Spinoza, and Leibniz as Continental rationalists. Especially significant in their grouping as Continental rationalists include their common adherence to Leibniz' principle of sufficient reason, and the idea that the fundamental nature of the universe could only be known through a priori reasoning.

Any discussion of Continental rationalism must essentially begin with a discussion of Rene Descartes' Meditations on First Philosophy, often considered the seminal work of this philosophical creed. Descartes' Meditations was first published in 1641, and it is made up of six different meditations. To begin, Descartes assumes that all of his prior beliefs were taken from either poor logic, or misleading information. Thus, Descartes attempts to discard all belief that is not completely certain. In the end, Descartes asserts that the only thing that he cannot doubt is his own existence. This understanding gave rise to his famous quote, cogito ergo sum (I think, therefore I am). Writes Descartes, I "have 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." After this, he tries to establish what can be known for certain.

In Discourse on Metaphysics, Gottfried Wilhelm Liebniz provides a short overview of his thoughts on metaphysics. In this work, he argues that all human knowledge is analytic in nature a posteriori. Further, all human knowledge comes from God, who "is an absolutely perfect being" (p. 3). To Liebniz, God possessed "supreme and infinite wisdom" (p. 3), and acted "in the most perfect matter 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, essentially argues that an understanding of knowledge ultimately arises from a metaphysics in which God in nature are deeply intertwined. Spinoza does not see God as simply the all powerful creator of the universe, but also as nature itself. Thus Spinoza argued that God and nature are essentially the same reality that underlies all of the universe. Nature contains an almost infinite number of attributes, including the physical and mental worlds, which were thought not to interact. Nature, in turn is a complete system that also encompasses the acts in thoughts of humans. Humans can only be happy if they understand this system, and their place within nature.

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

Leibniz' principle of sufficient reason can be considered to be one of the most important guiding principles for the Continental rationalists, including Descartes and Spinoza (Solomon). Like Leibniz, Descartes and Spinoza (as well as all other Continental rationalists) argued that "there is a complete, and completely rational, explanation for everything which occurs" (Hauptli), or in other words, "every event in the phenomenal world ... has a causal explanation (Solomon, p. 78).

Further, all three philosophers argued that way to the truth must begin with self-evident, a priori truths. The philosophers felt that knowledge or truth can be accessed through a deductive process. Notes Hauptli, Continental rationalists like Spinoza, Leibniz, and Descartes "held that it is only via a priori intellectual perceptions that we grasp the fundamental nature of the universe (the notions of substance, essence, etc.)."

Innate Ideas and Rationalism

A belief in innate principles or ideas is one of the key features out of continental rationalism. These ideas are seen as " certain, self-evident, and necessarily true" (Hauptli), and can include ideas such as "What is, is" and "It is impossible for the same thing to be, and not to be" (Hauptli).