The formalism of philosophy shown by Bertrand Russell and Ludwig Wittgenstein was further developed by a group of philosophers in Vienna and Berlin. In the early part of the twentieth century, they formed the Vienna Circle and the Berlin Circle with a doctrine known as logical positivism or logical empiricism.
Logical positivism showed formal logic underpinned the empiricist account of our knowledge of the world. Philosophers such as Rudolf Carnap and Hans Reichenbach, with other members of the Vienna Circle, claimed that the truths of logic and mathematics to be tautologies, and those of science were empirically verifiable and as such these two constituted the entire universe of meaningful judgements and anything else was just nonsense. The claims of ethics and aesthetics were subjective preferences. Theology and other metaphysics were pseudo-statements, neither true nor false, simply meaningless nonsense.
In the early nineteen thirties some members of the Vienna and Berlin Circles fled Germany due to the rise of Adolf Hitler and National Socialism in Germany and Austria. Many of them took homes in Britain and the USA, helping to promote logical positivism and analytic philosophy in the west.
Logical positivists thought that philosophy had a very limited function. They considered that philosophy dealt with the organisation of thoughts, rather than having any distinct thoughts of it’s own. The positivists adopted the principle of what they called, verificationism, which means that every meaningful statement is either logical or capable of being verified by experience. This in turn led the logical positivists to reject many of the traditional problems of philosophy, including those of metaphysics, as meaningless.