The doctrine that the special sciences—biology, chemistry, geology, economics, psychology—can eventually be reduced to one overarching science, usually thought of as physics. The reduction will be accomplished by providing an ‘image’ of the special science in the universal science, so that the laws of the special science turn out to be special cases of the universal way things are. The ideal was a central part of logical positivist thinking about science, and still influences many philosophers of a physicalist bent.