In Crossing the Threshold of Hope, Pope John Paul II spends a number of paragraphs on René Descartes and the way he ushered in a drastic change to Western thought. I’m very happy that the Holy Father chose to address this. Understanding the way in which science supplanted faith and kicked God out of the world is critical to understanding where we are as a society today.
I put Descartes in the forefront because he marks the beginning of a new era in the history of European thought and because this philosopher, who is certainly among the greatest that France has given the world, inaugurated the great anthropocentric shift in philosophy. “I think, therefore I am,” as previously mentioned, is the motto of modern rationalism. …
[Descartes] with his ontological proofs, distanced us from the philosophy of existence, and also from the traditional approaches of Saint Thomas which lead to God who is “autonomous existence,” Ipsum esse subsistens. By making subjective consciousness absolute, Descartes moves instead toward pure consciousness of the Absolute, which is pure thought. Only that which corresponds to human thought makes sense. The objective truth of this thought is not as important as the fact that something exists in human consciousness. …
Descartes marks the beginning of the development of the exact and natural sciences as well as the humanistic sciences in their new expression. He turns his back on metaphysics and concentrates on the philosophy of knowledge. Kant is the most notable representative of this movement.
Though the father of modern rationalism certainly cannot be blamed for the move away from Christianity, it is difficult not to acknowledge that he created the climate in which, in the modern era, such an estrangement became possible. It did not happen right away, but gradually.
In fact, about 150 years after Descartes, all that was fundamentally Christian in the tradition of European thought had already been pushed aside. This was the time of the Enlightenment in France, when pure rationalism held sway. The French Revolution, during the Reign of Terror, knocked down the altars dedicated to Christ, tossed crucifixes into the streets, introduced the cult of the goddess Reason. On the basis of this, there was a proclamation of Liberty, Equality, and Fraternity. The spiritual patrimony and, in particular, the moral patrimony of Christianity were thus torn from their evangelical foundation. In order to restore Christianity to its full vitality, it is essential that these return to that foundation.
Nevertheless, the process of turning away from the God of Jesus Christ, from the Gospel, and from the Eucharist did not bring about a rupture with a God who exists outside of the world. In fact, the God of the deists was always present; perhaps He was even present in the French Encyclopedists, in the work of Voltaire and of Jean-Jacques Rousseau, and even more so in Isaac Newton’s Philosophiae Naturalis Principia Mathematica, which marked the beginning of modern physics.
This God, however, is decidedly a god outside of the world. To a mentality shaped by a naturalistic consciousness of the world, a God present in the world appeared useless; similarly, a God working through man turned out to be useless to modern knowledge, to the modern science of man, which examines the workings of the conscious and the subconscious. The rationalism of the Enlightenment put to one side the true God—in particular, God the Redeemer.
The consequence was that man was supposed to live by his reason alone, as if God did not exist. Not only was it necessary to leave God out of the objective knowledge of the world, since the existence of a Creator or of Providence was in no way helpful to science, it was also necessary to act as if God did not exist, as if God were not interested in the world. The rationalism of the Enlightenment was able to accept a God outside of the world primarily because it was an unverifiable hypothesis. It was crucial, however, that such a God be expelled from the world.