Strategy and Manipulation in Medieval Elections

When developing electoral protocols, desiderata include a system which is transparent, non-manipulable, honest, and not open to strategizing. However, these desiderata are in tension with each other: Often, transparent electoral procedures are the least strategy resistant, and many honest procedures encourage manipulation. Thus, a balance between these different goals must be sought. In modern times, since the seminal result on vote manipulation, the Gibbard-Satterthwaite Theorem, much attention has been devoted to developing voting rules where manipulation is never in the best interest of the voters, or which are computationally too complex for the average bounded agent to be able to manipulate. In medieval times, such computational routes were generally not available, meaning that other constraints had to be put in place to discourage strategizing and manipulation. We discuss various voting rules and electoral procedures used in the Middle Ages in both ecclesiastical and secular context, highlighting some protocols with unique properties.