instrumentalism in its most common meaning, a kind of anti-realistic view of scientific theories wherein theories are construed as calculating devices or instruments for conveniently moving from a given set of observations to a predicted set of observations. As such the theoretical statements are not candidates for truth or reference, and the theories have no ontological import. This view of theories is grounded in a positive distinction between observation statements and theoretical statements, and the according of privileged epistemic status to the former. The view was fashionable during the era of positivism but then faded; it was recently revived, in large measure owing to the genuinely perplexing character of quantum theories in physics. ‘Instrumentalism’ has a different and much more general meaning associated with the pragmatic epistemology of Dewey. Deweyan instrumentalism is a general functional account of all concepts (scientific ones included) wherein the epistemic status of concepts and the rationality status of actions are seen as a function of their role in integrating, predicting, and controlling our concrete interactions with our experienced world. There is no positivistic distinction between observation and theory, and truth and reference give way to ‘warranted assertability.’ See also DEWEY, METAPHYSICAL REALISM , PHILOSOPHY OF SCIENCE , THEORETICAL TER. C.F.D.