What does empirical adequacy mean in Bas van Fraassen’s philosophy of science?

In the philosophy of science, Bas van Fraassen developed a position known as constructive empiricism. Within this framework, he argues that the primary aim of science is not to produce theories that are literally true in their entirety, but rather to construct theories that are "empirically adequate."1

A theory is considered empirically adequate if it captures or predicts all relevant truths regarding observable phenomena. Essentially, this means that everything the theory says about the observable world—the matters of fact that can be recorded through observation and experimentation—must be true.1

Van Fraassen’s view distinguishes between observable and unobservable entities, suggesting that while a theory must be accurate regarding the former, it does not necessarily need to be true regarding the latter (such as theoretical entities that cannot be directly observed). By focusing on empirical adequacy, van Fraassen provides an antirealist alternative to the scientific realist claim that science aims for a literally true account of the entire world, including its unobservable aspects.1