In lecture six, we investigate the rationalist tradition, tracing its roots from Plato to modern thinkers like Descartes and Leibniz. We focus on how rationalists respond to skepticism, arguing that knowledge can be gained independently of experience through innate ideas and a priori truths. We examine Descartes’ “cogito ergo sum” and mind-body dualism, as well as Leibniz’s analytic and synthetic distinctions and his defense of synthetic a priori knowledge. Our discussion concludes by highlighting the fundamental disagreement between rationalists and empiricists about whether all knowledge comes from experience or whether the mind contributes its own innate structures to organize and understand reality.