It is not inacurate to say that from 1928 to 1936 Carnap was a member of the Vienna Circle, even though during this period he was not always present in Vienna. During this years, which spanned roughly the period from the Aufbau to Testability and Meaning, he worked or at least discussed frequently with the members of the group.
However, traditionally it has been difficult to form a proper view of the development of Carnap's ideas throughout this period, mainly because of three errors which have persisted in the commonly accepted historical interpretation of Carnap and the Vienna Circle: emphasis on the Circle as a unit rather than a collective of individuals; insistence on verificationism as the defining characteristic of Logical Positivism; and the systematic abstraction of the work of the Circle from its historical context. As against this historically distorted image, this book argues for an alternative reading, evaluating the different influences on Carnap of Schlick, Wittgenstein, Neurath and Popper, and making sense of Carnap's evolution from physicalism to phenomenalism and the syntactic point of view.