Modern philosophy is philosophy developed in the modern era and associated with modernity. It is not a specific doctrine or school (and thus should not be confused with Modernism), although there are certain assumptions common to much of it, which helps to distinguish it from earlier philosophy. The 17th and early 20th centuries roughly mark the beginning and the end of modern philosophy. How much of the Renaissance should be included is a matter for dispute; likewise modernity may or may not have ended in the twentieth century and been replaced by postmodernity. How one decides these questions will determine the scope of one's use of the term "modern philosophy." Modern Western philosophy How much of Renaissance intellectual history is part of modern philosophy is disputed: the Early Renaissance is often considered less modern and more medieval compared to the later High Renaissance. By the 17th and 18th centuries the major figures in philosophy of mind, epistemology, and metaphysics were roughly divided into two main groups. The "Rationalists," mostly in France and Germany, argued all knowledge must begin from certain "innate ideas" in the mind. Major rationalists were Descartes, Baruch Spinoza, Gottfried Leibniz, and Nicolas Malebranche. The "Empiricists," by contrast, held that knowledge must begin with sensory experience. Major figures in this line of thought are John Locke, George Berkeley, and David Hume (These are retrospective categories, for which Kant is largely responsible). Ethics and political philosophy are usually not subsumed under these categories, though all these philosophers worked in ethics, in their own distinctive styles. Other important figures in political philosophy include Thomas Hobbes and Jean-Jacques Rousseau. In the late eighteenth century Immanuel Kant set forth a groundbreaking philosophical system which claimed to bring unity to rationalism and empiricism. Whether or not he was right, he did not entirely succeed in ending philosophical dispute. Kant sparked a storm of philosophical work in Germany in the early nineteenth century, beginning with German idealism. The characteristic theme of idealism was that the world and the mind equally must be understood according to the same categories; it culminated in the work of Georg Wilhelm Friedrich Hegel, who among many other things said that "The real is rational; the rational is real." Hegel's work was carried in many directions by his followers and critics. Karl Marx appropriated both Hegel's philosophy of history and the empirical ethics dominant in Britain, transforming Hegel's ideas into