The following is an answer I wrote to this question: Describe and discuss the key assumptions made by Descartes as part of “the age of reason”—how did he and his followers challenge earlier Christian thought? This is one of three questions I answered for my “final exam” for my Reformation Theology class. Here’s my answer:

Rene Descartes was a French philosopher who changed the landscape of the day. He originally started out as a military man, but didn’t find satisfaction in this career. After this he set out to apply his mathematical knowledge (geometry) to give people a certainty about how people know (epistemology); and yet he began to realize that he would need to do more than this to establish a substantial epistemological foundation.

He therefore began a methodological system of doubt–skepticism (e.g. pyrohnic skepticism), whereby he doubted everything possible. He finally doubted himself down to himself—therefore he had his ergo cogito sum (I think therefore I am). He called his new system, his “clear and innate ideas.” He believed that he had established an incorrigible foundation (basic beliefs) from which all thought could have a certain foundation. (e.g. foundationalism) from which to build.

He then extended his new system out to the existence of God, and then worked back to all contingent reality showing it to be most certainly there, based on his original foundation—”I think therefore I am.” Descartes was the fountain head of “rationalist” thought. He gave man a new optimism about what he could know. And this optimism started with the “certainty” of man’s reason over against the certainty of “revelational knowledge” (the Bible) and therefore starting with God. Some significant figures who were influenced by Cartesianism (some positively and negatively) were: Malebranche, Spinoza, and Pascal. The first two, Malbranche and Spinoza, thought Cartesianism was great. Malebranche then applied Cartesianism to his thought, and thus began to equate being a philosopher as synonymous with being a Christian—he ultimately became a pantheist. Likewise Spinoza believed (using Cartesianism) that Christians needed to flush everything they had based their “knowing” on (i.e. the Bible, Creeds, and the Church) and thus start over with the “certainty” of man’s “reason” as the first principle—He likewise became a pantheist. Pascal, on the other hand, believed that Cartesianism was a detriment to man, and thus countered the optimism of Malebranch and Spinoza by stating or asserting that he believed man’s reason (alone) only ended in chaos.

Therefore it can be seen that Descartes’ principles of knowing began to undermine the authority of scripture, and replace this with the authority of reason. Some of his followers (i.e. Malebranch and Spinoza) extended Descartes’ thought out, and showed that man no longer needed the God of the Bible. It started a movement that began to allow man to have a sense of autonomy from God.

This new found confidence in man’s reason thus gave rise to the thought of John Locke (e.g. rationalism and empericism), and George Berkely—ultimately culminating in David Hume who destroyed man’s confidence in reason (via skepticism). Immanuel Kant picked up the pieces, so to speak. Deism also came into play at this point in the history of ideas.

People like Richard Simon and John LeClerq also began to debate the trustworthiness of the Bible; and the Hugenot Pierre Bayle picked up on this and wrote a manual against the authenticity of the Scriptures thus giving ammo to deists for years to come (higher critics of today operate from the same assumptions that many of these men of old articulated). Descartes’ impact was to initiate a movement that exalted man’s reason over God’s revelation.

Question: How is reason exalted over revelation in the Evangelical church, from your perspective?