René Descartes (1596-1650) was a seminal French philosopher, mathematician, and scientist. He is considered a founder of modern philosophy due to promoting observation and experiment over scholasticism. He is renowned for developing analytic geometry, which uses algebra to describe geometry. Descartes also pioneered standard mathematical notation like using exponents and representing unknowns with variables like x, y, z. He believed algebra could automate and mechanize reasoning about abstract concepts.