The aim of the group was to restate ideas about both scientific knowledge and philosophy and establish a form of philosophy that would be close to science, unlike German idealism. The members did not think that philosophy had a positive content of its own, or even a distinct epistemology or theory of knowledge. Rather, philosophy should study the knowledge methods and claims of science and justify them. For example, they thought that Albert Einstein’s theory of relativity had shown that philosophers could not have the last word on either space or time, as Kantians believed. Arithmetic was believed to be reducible to logic, and synthetic a priori knowledge (rational knowledge derived from thought alone that was true to experience) was unnecessary. The principle of verification, or verificationism, was their main tenet. Whatever claims to knowledge could not be verified in the sciences was simply not knowledge.