Positivism is an empiricist philosophical theory that holds that all genuine knowledge is either true by definition or positive—meaning a posteriori facts derived by reason and logic from sensory experience. Other ways of knowing, such as theology, metaphysics, intuition, or introspection are rejected or considered meaningless.
Although the positivist approach has been a recurrent theme in the history of western thought, modern positivism was first articulated in the early 19th century by Auguste Comte. His school of sociological positivism holds that society, like the physical world, operates according to general laws. After Comte, positivist schools arose in logic, psychology, economics, historiography, and other fields of thought. Generally, positivists attempted to introduce scientific methods to their respective fields. Since the turn of the 20th century, positivism has declined under criticism from antipositivists and critical theorists, among others, for its alleged scientism, reductionism, overgeneralizations, and methodological limitations.
2. In the field of scientific research, a positivistic mentality took hold which not only abandoned the Christian vision of the world, but more especially rejected every appeal to a metaphysical or moral vision. It follows that certain scientists, lacking any ethical point of reference, are in danger of putting at the centre of their concerns something other than the human person and the entirety of the person's life. Further still, some of these, sensing the opportunities of technological progress, seem to succumb not only to a market-based logic, but also to the temptation of a quasi-divine power over nature and even over the human being. As a result of the crisis of rationalism, what has appeared finally is nihilism. As a philosophy of nothingness, it has a certain attraction for people of our time. Its adherents claim that the search is an end in itself, without any hope or possibility of ever attaining the goal of truth. In the nihilist interpretation, life is no more than an occasion for sensations and experiences in which the ephemeral has pride of place. Nihilism is at the root of the widespread mentality which claims that a definitive commitment should no longer be made, because everything is fleeting and provisional. (Papal Encyclical, Fides et Ratio, 14 September 1998).