 Semantically, realism is committed to a literal interpretation of scientific claims about the world. In common parlance, realists take theoretical statements at “face value”. According to realism, claims about scientific objects, events, processes, properties, and relations (I will use the term “scientific entity” as a generic term for these sorts of things henceforth), whether they be observable or unobservable, should be construed literally as having truth values, whether true or false. This semantic commitment contrasts primarily with those of certain “instrumentalist” epistemologies of science, which interpret descriptions of unobservables simply as instruments for the prediction of observable phenomena, or for systematizing observation reports. Traditionally, instrumentalism holds that claims about unobservable things have no literal meaning at all (though the term is often used more liberally in connection with some antirealist positions today). Some antirealists contend that claims involving unobservables should not be interpreted literally, but as elliptical for corresponding claims about observables. These positions are described in more detail in  section 4.