Concerning the shift from objective rationality to modern irrationality, Francis Schaeffer writes:
The shift spread gradually, and in three different ways. People did not suddenly wake up one morning and find that it had permeated everywhere at once.
First of all it spread geographically. The ideas began in German y and spread outward. They affected the Continent first, then crossed the Channel to England, and then the Atlantic to America. Secondly, it spread through society, from the real intellectual to the more educated, down to the workers, reaching the upper middle class last of all. Thirdly, it spread as represented in the diagram, from one discipline to another, beginning with the philosophers and ending with the theologians. Theology has been last for a long time. It is curious to me, in studying this whole cultural drift, that so many pick up the latest theological fashion and hail it as something new. But in fact, what the new theology is now saying has already been said previously in each of the other disciplines.
(The God Who Is There, 1.1)