The definition of piracy has long been a matter of interest to philosophers and politicians alike. In this chapter, we consider the philosophical and political interest in piracy by focusing on a dissertation published in Uppsala, Sweden, in 1716 by Magnus Thelaus (1687–1765), entitled: Dissertatio gradualis de piratica [On Piracy]. Of Thelaus himself very little is known, beyond the fact that after taking his Master's degree he became a lecturer in oriental languages and theology at Uppsala in 1733, and eventually rose to become a Dean of the Lutheran church. In this chapter, we use Thelaus's De piratica to explore the malleable meanings of piracy in eighteenth-century Swedish philosophical and scholarly discourse against the backdrop of Sweden's dire diplomatic situation. Various chapters in this book have considered the striking concurrence that characterized European and non-European notions of piracy in the seventeenth and eighteenth centuries. This was not simply a matter of the coexistence of divergent understandings and cultural practices around the world, but, as we show here, of the entanglement of different discourses of piracy within one state. In this chapter, we reveal how a conventional scholarly articulation of the pirate as a “common enemy of all humankind” coexisted with an urgent but almost secret debate about the uses that may be made of pirates in statecraft.

The timing of De piratica in 1716 was especially significant. The early decades of the eighteenth century were a pivotal period in the extension of European state sovereignty at sea and with it, of the claims of European international law.