Saving unobservable phenomena

In this paper I argue-against van Fraassen's constructive empiricism-that the practice of saving phenomena is much broader than usually thought, and includes unobservable phenomena as well as observable ones. My argument turns on the distinction between data and phenomena: I discuss how unobservable phenomena manifest themselves in data models and how theoretical models able to save them are chosen. I present a paradigmatic case study taken from the history of particle physics to illustrate my argument. The first aim of this paper is to draw attention to the experimental practice of saving unobservable phenomena, which philosophers have overlooked for too long. The second aim is to explore some far-reaching implications this practice may have for the debate on scientific realism and constructive empiricism.