Twentieth-century philosophy

1. Inaugural projects: Realism and analysis

Although twentieth-century philosophy contains many diverse methods and projects, its programmatic origins might be dated from two events that occurred in 1898 and 1901–1902, respectively. The first of these was the decision of the young Bertrand Russell, following a few months after that of his Cambridge colleague G. E. Moore, decisively to break with the Hegelian philosophy that was then dominant in Britain, pursuing instead a realist project of the analysis of concepts into their simpler constituent parts. The second was Edmund Husserl’s publication, in two volumes, of his massive Logical Investigations, the work which he later saw as his true “breakthrough” to phenomenology and its characteristic methods of the analysis and description of the meaningful structure of conscious experience and intentionality. For both philosophers, these developments involved methodologically and substantively rejecting the forms of idealism and historicism that had broadly dominated nineteenth-century philosophy (see Nineteenth-century philosophy) in favor of broad new projects which they saw as more scientific and realist in spirit. Both rejected the idealist view that ultimate or final truth can be found only on the level of a conception of knowledge as absolute or whole, proposing instead to analyze the contents of experience, language, and thinking as separate and individual items involving discrete, particular claims to truth. Along with this, both rejected any conception of the contents to be analyzed as themselves irreducibly mind-dependent, or ultimately grounded in individual, subjective acts of conception or thinking. Instead, both pursued the analysis and description of what they saw as objective contents or aspects of sense or meaning: those aspects, in other words, responsible for the objective truth of a sentence expressing them, a thought grasping them, or an experience exhibiting them, quite independently of the temporal characteristics of the particular vehicles (the particular thought, experience, or sentence) which captured or expressed them in each case.

In this conception, both were further emboldened by the new developments then occurring in logic and the foundations of mathematics (see Logic in the early 20th century).

Drawing on an idea of the objective content of thought which had been suggested early in the nineteenth century by Hermann Lotze and Bernard Bolzano, Gottlob Frege in 1879 developed his Begriffsschrift, or system of formal, symbolic logic that was intended to display the structure of inference in mathematical proofs. Here, Frege significantly developed the apparatus of quantification – the treatment of expressions such as “all,” “some,” and “there exists” – which remains foundational for symbolic logic today. In later works, Frege proposed and pursued the project which became known as logicism: that of a reduction of arithmetic to symbolic logic together with the set theory that had been proposed and developed by Georg Cantor over the preceding decades, and in 1892 Frege proposed an influential distinction between the sense, or content, of a linguistic term or sentence and its reference, or object. Throughout his career, Frege argued vigorously against the position (which can be traced back to J. S. Mill and various nineteenth-century psychologists and logicians) of psychologism with respect to logic and mathematics, on which logical and mathematical laws or rules are to be reduced to, or explained in terms of, the psychological regularities of thinking rather than the contents of what is thought. Frege’s new logic, together with Peano’s postulates of arithmetic, proved decisive for Russell’s articulation of the project of analysis and its application not only to the foundations of mathematics broadly but also to traditional problems of epistemology, semantics, and ontology. At the same time, the anti-psychologism of which Husserl had earlier become convinced founded his conception of the logically articulated contents or meanings to be described by means of phenomenological reflection.

The first years of the twentieth century also witnessed the origins of what would become several other prominent projects of twentieth-century philosophy. In 1907, William James published a series of lectures on pragmatism, the philosophical approach he had derived from what C. S. Peirce had earlier called his project of “pragmaticism.” At the center of the project for both philosophers was a conception of truth and meaning as comprehensible in terms of their practical consequences or effects, and an attempt to overcome divisions between scientific and religious, speculative, and metaphysical thought by means of this conception. In Geneva, Ferdinand de Saussure gave the lectures that were published posthumously as his Course in General Linguistics: these lectures envisioned language as a total system or structure of signs, and “semiology” as a scientific approach to the study of this structure. Meanwhile, Sigmund Freud’s The Interpretation of Dreams, published in 1899, inaugurated the application of psychoanalytic techniques of interpretation to the study of the unconscious and to the broader question of the deep structure underlying ordinary conscious experience and linguistic meaning.