The King and the Marquis

In an unknown date of the eighth or ninth century E. V., the Khazar Empire adopted Judaism as its State religion. A legend of how this choice was made makes a quite interesting textbook case of the use of the Condorcet rule, and allows once more to appreciate its merits. Possibly more interestingly, it also illustrates a failure of the Condorcet rule. We know that in the absence of the Condorcet cycle the Condorcet rule is immune from strategic voting; as we will see, actually it is exposed to it, albeit in a peculiar way and in a peculiar (but relevant) setting. This very short note deals both with the use of the rule by the King of the Khazars according to the legend (sect. 3), and with its failure (sect. 4 and 5). A preliminary section summarizes very briefly the history of the conversion.