G. E. Moore’s main contributions to philosophy were in the areas of metaphysics, epistemology, ethics, and philosophical methodology. In epistemology, Moore is remembered as a stalwart defender of commonsense realism. Rejecting skepticism on the one hand, and, on the other, metaphysical theories that would invalidate the commonsense beliefs of “ordinary people” (non-philosophers), Moore articulated three different versions of a commonsense- realist epistemology over the course of his career.
According to data I researched Moore’s epistemological interest also motivated much of his metaphysical work, which to a large extent was focused on the ontology of cognition. In this regard, Moore was an important voice in the discussion of sense-data that dominated Anglo- American epistemology in the early twentieth century. In ethics, Moore is famous for driving home the difference between moral and non-moral properties, which he cashed-out in terms of the non-natural and the natural.
Moore’s classification of the moral as non-natural was to be one of the hinges upon which moral philosophy in the Anglo- American academy turned until roughly 1960. Moore’s approach to philosophizing involved focusing on narrow problems and avoiding grand synthesis. His method was to scrutinize the meanings of the key terms in which philosophers expressed themselves while maintaining an implicit commitment to the ideals of clarity, rigor, and argumentation. This aspect of his philosophical style was sufficiently novel and conspicuous that many saw it as an innovation in philosophical methodology.
Moore is widely acknowledged as a founder of analytic philosophy, the kind of philosophy that has dominated the academy in Britain and the United States since roughly the 1930s. Moore also had a significant influence outside the academic philosophy, through his contacts in the Cambridge Apostles and the Bloomsbury group. In both academic spheres, Moore’s influence was due in no small part to his exceptional personality and moral character. One of the most important parts of Moore’s philosophical development was his break from the idealism that dominated British philosophy (as represented in the works of his former teachers F.
H. Bradley and John McTaggart), and his defense of what he regarded as a “common sense” form of realism. In his 1925 essay “A Defense of Common Sense”, he argued against idealism and skepticism toward the external world on the grounds that they could not give reasons to accept their metaphysical premises that were more plausible than the reasons we have to accept the common sense claims about our knowledge of the world that skeptics and idealists must deny.
He famously put the point into dramatic relief with his 1939 essay “Proof of an External World”, in which he gave a common sense argument against skepticism by raising his right hand and saying “Here is one hand,” and then raising his left and saying “And here is another,” then concluding that there are at least two external objects in the world, and therefore that he knows (by this argument) that an external world exists.
Not surprisingly, not everyone inclined to skeptical doubts found Moore’s method of argument entirely convincing; Moore, however, defends his argument on the grounds that skeptical arguments seem invariably to require an appeal to “philosophical intuitions” that we have considerably less reason to accept than we have for the common sense claims that they supposedly refute.