Continental Rationalism Characterized


     Copyright © 2014 Bruce W. Hauptli


The Continental Rationalists (Descartes, Spinoza, and Leibniz) each helped to cement the downfall of the Medieval world-view and the rise of the modern scientific world-view.  A central tenet of the Medieval period was that faith and reason could not contradict one another:


the natural dictates of reason must certainly be true; it is impossible to think of their being otherwise.  Nor again is it permissible to believe that the tenets of faith are false, being so evidently confirmed by God.  Since therefore falsehood alone is contrary to truth, it is impossible for the truth of faith to be contrary to the principles known by natural reason.[1] 


The Medieval view was that faith and reason co-operated to depict a world in which everything accorded with the divine purpose.  While this picture was the dominant one for about a thousand years (from about 400-1400 C.E.),[2] with the Renaissance (1400-1600) this world-view came under substantial pressure. 


     The Rationalists’ period is marked by a change in the attitude toward the Medieval institutions and beliefs.  These philosophers did not so much ask new questions, instead, they endeavored to provide “new” answers.  These answers weren’t wholly different from the sorts of answers offered by the Medievals, but they were offered in a new spirit, with a new method, and in a new manner.[3]  The Rationalists’ fundamental break with the previous tradition was an unrelenting “faith” in human reason.  They held we could arrive at knowledge unaided by religious faith or revelation.[4] 


     For the Continental Rationalists, Leibniz’ principle of sufficient reason may be considered the basic principle: they all held that there is a complete, and completely rational, explanation for everything which occurs.  It should be stressed that their conception of reason is that knowledge (or truth) is arranged in a deductive system, and that one must “begin” with self-evident, a priori truths of which we can be certain.  That is, their “faith in reason” was a faith in a priori reasoning—they did not believe that our sensory experience could provide us with knowledge of the world.  Instead, the Continental Rationalists 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.). 


     According to the Continental Rationalists, the appropriate methodology for building upon the self-evident truths is the deductive axiomatic method of mathematics (as especially exemplified in geometry) wherein theorems are derived from axioms and postulates.  Of course, the truth of the theorems is dependent upon the truth of these postulates.  The Continental Rationalists believed that these axioms and postulates were not to be accepted on faith but, rather, that they must be known by and guaranteed by some sort of intellectual understanding (or rational intuition).  These intuitions showed certain facts to be necessary truths and upon this sort of a priori, rational, and certain basis, the Continental Rationalists would ground all of our knowledge.  They did not hold, as many now do, that logical truths (tautologies) are mere “truths of language” (which give us no substantial information about the way the world is).  Instead, they held that the necessary truths they which they relied upon reflected necessary facts and gave us (certain) knowledge of the basic ways of the world. 


     In saying that the Continental Rationalists’ conception of reason is that knowledge (or truth) is arranged in a deductive system, we speak about both their epistemology and their metaphysics.  Metaphysically speaking, they hold that the world has a fundamentally deductive structure.  Moreover, for all of them the ontological argument occupies position of central metaphysical importance.  The fact “exposed” by this proof provides the “metaphysical ground” for the whole system of truth which constitutes the created universe.  Epistemologically speaking, of course, this “ground” provides the explanation for all the other truths in the total “system” of truths. 


     At the core of the Continental Rationalists’ orientations, then, are what are called innate principles or ideas.  These “ideas” express the intellectual intuitions which are the heart of their systems. The clearest example of an innate idea is the idea of a deity.  Standard examples of innate principles for these thinkers (claims which they hold to be know a priori, and which are held to be intellectual intuitions that are certain, self-evident, and necessarily true) include: “What is, is” and “It is impossible for the same thing to be, and not to be.”  As noted in the Encyclopedia Britannica:


the Cartesian metaphysics is the fountainhead of Rationalism in modern philosophy, for it suggests that the mathematical criterion of clarity, distinctness, and absence of contradiction among ideas are the ultimate test of meaningfulness and truth.  This stance is profoundly antiempirical.  Bacon, who had said that “reasoners resemble spiders who make cobwebs out of their own substance,” might well have said so of Descartes, for the Cartesian self is just such a substance from which the idea of God originates and with which all deductive reasoning begins.  Yet for Descartes the understanding is vastly superior to the senses, and, in the question of what constitutes truth in science, only man’s reason can ultimately decide.[5] 


     A major problem for Continental Rationalism is directly evident when we note the diversity of basic postulates which the different rationalists advance, and the radically different conclusions which they draw from shared principles, postulates, or ideas.  Since they wished to offer objective theories (which all rational thinkers would have to accept), their differences at this fundamental level were a matter of no small concern. 


     Another problem with their orientation is that they have a great deal of difficulty admitting any degree of contingency into their systems.  Since their model of knowledge is one which begins with necessary truths, since their systems posit deductive connections between truths, and since they hold that everything is so explicable, there seems little room for contingency in the universe.  After all, deductive consequences of necessary truths are themselves necessary. 


Notes: [click on note number to return to the text for the note]

[1] Aquinas, Summa Contra Gentiles [~1260], I. 7. 

[2] This includes the Medieval Renaissance (1100-1300): where there was translation of Greek texts (Euclid, Ptolemy, Aristotle); study of Aristotle’s methods of observation, experiment, and logical reasoning; and work to reconcile faith and the new forms of reasoning.  Aquinas (1226-1274) was especially concerned with the latter.  William of Ockham (1300-1349) denied Aquinas’ project because religious claims must be taken only on faith—he rejected Medieval metaphysics and contended that non-revealed claims must be based on experience. 

[3] In his “Introduction,” Martin Hollis maintains that “the novelty of Rationalism lies in its method of enquiry, which owed more to logic and mathematics and, at the same time, to scientific experiment than any before.  The results of the method, however, often owed more to the past than the Rationalists admitted.  Presumptions made about God, about human nature and about the character of rational order...” (Martin Hollis, “Introduction” to The Light of Reason: Rationalist Philosophers of the 17th Century, ed. Martin Hollis [London: Fontana/Collins, 1973], pp. 9-36, pp. 10-11). 

[4] Of course, this·is·one reason·for·also looking at, and contrasting, their orientation with, Pascal’s orientation. 

[5] “Philosophy, history of,” Encyclopedia Britannica Online, <>, accessed 19 August 1999. 

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Last revised on: 11/04/2014