Logical positivism (later and more accurately called logical empiricism) is a school of philosophy that combines empiricism—the idea that observational evidence is indispensable for knowledge of the world we live in—with a version of rationalism—the idea that our knowledge includes a component that is not derived from observation.

 

A central tenet of logical positivism is that metaphysical, theological, and ethical sentences are "cognitively meaningless," and serve merely to express the feelings or desires of a speaker. Only mathematical, logical and scientific statements are literally meaningful, or have truth values.

 

Logical positivism grew from the discussions of the Moritz Schlick's Vienna Circle and Hans Reichenbach's Berlin Circle in the 1920s and 1930s. The movement is known for its espousal of verificationism, its admiration for science and technical rigor, and its commitment to the analytic-synthetic distinction. The logical positivists agreed that there are no synthetic a priori propositions, though they disagreed with earlier positivists, such as Ernst Mach, who held that the a priori had no place in science.