G. E. Moore

Studying at Trinity College, Cambridge, George Edward Moore (1873–1958) rebelled against British absolute idealism, advocating ordinary language and common sense realism. In 'Principia Ethica' (1903), he argued that 'the good' is a simple, non-natural, unanalyzable property, coining the term 'naturalistic fallacy' for attempts to define good in terms of pleasure, evolution, or nature.

In 1939, in 'Proof of an External World', Moore famously raised his right hand and said 'Here is one hand', then raised his left hand and said 'and here is another', providing a commonsensical refutation of radical skepticism. He was a central intellectual mentor to the Bloomsbury Group.