Explain precisely how Descartes' thinking is such a radical shift from Medieval thinking.

Descartes' thinking was a radical shift from Medieval thinking because he emphasized reason and scientific knowledge instead of religious tradition.

Rene Descartes was a prominent French philosopher, the founder of modern philosophy. He was a rationalist who systematically sought to doubt everything possible. His goal was to find a solid foundation for certain information. Descartes was heavily influenced by advances in physics and astronomy and one of the central figures of the scientific revolution. He first gave an idea of what natural science would offer in the future.

His rationalist theories, his vocation to find logical explanations for all events and his constant criticism of traditions systematically confronted philosophies based on medieval beliefs and Aristotelian philosophers, because they had deep roots in religious beliefs and the cultural traditions of Ancient Greece.