Comte believed that the appreciation of the past and the ability to build on it towards the future was key in transitioning from the theological and metaphysical phases. The idea of progress was central to Comte's new science, sociology. Sociology would "lead to the historical consideration of every science" because "the history of one science, including pure political history, would make no sense unless it was attached to the study of the general progress of all of humanity".  As Comte would say: "from science comes prediction; from prediction comes action."  It is a philosophy of human intellectual development that culminated in science. The irony of this series of phases is that though Comte attempted to prove that human development has to go through these three stages, it seems that the positivist stage is far from becoming a realization. This is due to two truths: The positivist phase requires having a complete understanding of the universe and world around us and requires that society should never know if it is in this positivist phase. Anthony Giddens argues that since humanity constantly uses science to discover and research new things, humanity never progresses beyond the second metaphysical phase. 
Popper puzzled over the stark contrast between the non-scientific character of Freud and Adler 's theories in the field of psychology and the revolution set off by Einstein 's theory of relativity in physics in the early 20th century. Popper thought that Einstein's theory, as a theory properly grounded in scientific thought and method, was highly "risky", in the sense that it was possible to deduce consequences from it which were, in the light of the then-dominant Newtonian physics , highly improbable (., that light is deflected towards solid bodies—confirmed by Eddington's experiments in 1919 ), and which would, if they turned out to be false, falsify the whole theory. In contrast, nothing could, even in principle, falsify psychoanalytic theories. He thus came to the conclusion that psychoanalytic theories had more in common with primitive myths than with genuine science.