The "object theoretic operational view" suggests a new structure of physical knowledge. This view takes branches of physics as basic units. Its main concepts are primary (PIO) and secondary (SIO) ideal objects with the explicit definition of SIO through PIO and the implicit definition of PIOs within appropriate systems of statements, called a "nucleus of a branch of physics" (NBP). Within an NBP (which has a definite structure) the focus shifts from discovering "laws of nature" to definition of a physical (...) object (system) and its states, and the distinct notion "measurable" replaces the vague notion "observable". On this basis the roles of physical models and measurements within physics, as well as two types (PIO- and SIO- type) of theories, activity, and experiment are discussed, and a different junction of "realism” and "constructivism" is presented. (shrink)

In this paper, I argue that the conceptual changes that occurred in the structure of physical knowledge during the second half of the 19th century, are reflected by the concept of the “primary ideal object” and its implicit definition within appropriate systems of statements, called a “nucleus of a branch of physics”. Within an NBP focus shifts away from discovering “laws of nature” to observations of a physical object and its states, while the distinct notion of “measurable” replaces the vague (...) notion “observable”. On the basis of this notion, the roles of physical models and measurements within physics, different kinds of work, experiments, and laws are discussed. Next follows a discussion of different levels of change in science, after which this distinction is compared to Kuhn’s model. Finally, I present a new combination of “realism” and “constructivism”, which differs from both the “constructive empiricism” of van Fraassen and from different “empirical realisms”. (shrink)