G. E. Moore’s most influential book. In it, he defines the subject of ethics as the general enquiry into the question “what is good?” and famously contends that the predicate “good” is indefinable. Moore claims that whatever definition is offered of the predicate, “it may be always asked, with significance, of the complex so defined, whether it is itself good,” an argument that would later come to be known as the “open question” argument. To fail to accept its conclusion and instead to identify “good” with some other quality or list of qualities is, according to Moore,..." data-title="Книга Principia Ethica">