Metaphysics

Kant himself rejected metaphysics, considered as an attempt to know objects outside experience. Forms of that position characterized three major recent philosophical movements that drew on his emphasis on the thinking self and his devotion to empiricism.

American Pragmatism.

This movement emphasized, following Kant and in some cases Hegel, the role of concepts in experience. John Dewey (1859–1952) argued that concepts distort our understanding of the unity of nature. Charles Peirce (1839–1914) similarly took conceptual analysis to demonstrate that the propositions of traditional metaphysics are nonsensical. William James (1842–1910) defended the use of concepts and took metaphysics to be the task of understanding why people organize experience the way they do. Some traditional metaphysical notions remained in American Pragmatism. Peirce, for example, defended an account of generals, a theory of natural kinds. However, the movement was generally critical of traditional, a priori metaphysics.

Phenomenology and existentialism.

These movements, which started perhaps with the works of Nietzsche, emphasized the importance of perspective for undermining or perhaps reassessing metaphysics.

Phenomenology is the study of things as one experiences them. In Ideas, Edmund Husserl (1859–1938) argued that this project requires setting aside questions of existence, which amounts to making questions of metaphysics secondary to questions of experience. Martin Heidegger (1889–1976), slightly differently, made questions of existence, or being, just questions of experience. The study of being is not, for Heidegger, then, the study of the being of fundamental things in the universe that are independent of experience but instead the study of the being of things as they are experienced and, perhaps more important, formed and conceived by the thinker. Existentialism, perhaps best known from the works of Jean-Paul Sartre (1905–1980), in the most general terms is the conclusion, from either of these positions, that there are no metaphysical facts about the world, with the result that if one really needs such facts, as Kant suggested, one must either create them or insist upon what one has no claim to know.

Logical positivism.

Ludwig Wittgenstein (1889–1951) and Rudolf Carnap (1891–1970) derived, largely from Kant, the view that knowledge is only of objects of experience. Logical positivists held, furthermore, that as terms apply meaningfully only to objects of experience, metaphysical claims are not merely false or mistaken but nonsensical. The movement was largely responsible for making language and its meaning the focus of a great deal of recent philosophical inquiry in metaphysics and also in epistemology and ethics.