raionalism

Rationalism, in philosophy, is the view that reason is the chief source of knowledge and that certain knowledge can be attained independently of sensory experience. Proponents emphasize a priori knowledge—truths that are knowable through reason alone, often by deduction—from self-evident principles or innate ideas. Rationalists argue that the mind imposes order on the world, and that careful reflection can reveal necessary truths about reality, mathematics, logic, and ethics.

Modern rationalism arose in 17th- and 18th-century Europe as a reaction against reliance on sensory observation alone. Key figures include René Descartes, Baruch Spinoza, and Gottfried Wilhelm Leibniz. Descartes advocates methodological doubt and the famous cogito, "I think, therefore I am," as a foundation for certainty. Spinoza develops a system of deductive reasoning from clear and distinct ideas, while Leibniz develops a program of rational architecture and the notion of possible worlds. Together they argued that knowledge can be established through deduction and the analysis of concepts.

Rationalism is often contrasted with empiricism, which emphasizes observation and induction from the senses as the primary path to knowledge. Many later philosophers, notably Immanuel Kant, attempted a synthesis, arguing that while knowledge begins with experience, some structures of understanding are a priori.

Rationalism has influenced mathematics, logic, and the philosophy of science, shaping debates about the sources and limits of human understanding. Critics challenge the sufficiency of reason alone to justify knowledge about the empirical world and highlight the role of experience in confirming hypotheses.