Karl Popper’s critique of idealism manifests itself with the application of his method, falsificationism, to metaphysics, epistemology, and social and political philosophy. According to Popper, who identifies himself as a philosophical realist, idealism has emerged as a result of the idea that reality cannot be known by reason and of the search for certainty which is erroneous, and it has begotten two mistaken and detrimental views. These views are historicism, the notion that history has an irresistible course, and holism, the notion that social wholes are organic structures that amount to more than the individuals constituting them. Historicism and holism have become the philosophical underpinnings of closed societies throughout history, such as the totalitarian regimes of the 20th century. Therefore, with a practical leaning, Popper actually takes aim at these pernicious consequences of idealism while criticizing it. In this study, idealism and the contours of Popper’s philosophy are examined, and then Popper’s metaphysical, epistemological, social, and political critiques against idealism are investigated.
Keywords: Karl Popper, idealism, historicism, holism, falsificationism