Catherine The Great similar to many rulers from the period she was ruling was known as an absolute monarch. She mostly reigned without allowing anyone to interfere in her decisions, but through the influence of Enlightenment movement she made some good decisions. Among them are the mentioned ones - expanded education, reformed legal system and improvement of life conditions for commoners.
The idea that Descartes did contribute to the Scientific Revolution was logic and mathematics that could figure out the uncertainties of existence. Rene Descartes was considered a modern philosopher and published Discourse of Method which was standard of scientific method.