  Beginning in the mid-thirteenth century, the debate between reductive and non-reductive realists is often carried out in the context of the discussion whether relations are identical to their foundations. (This is the context, for example, in which Scotus and Ockham develop their positions.) By the mid-thirteenth century, moreover, it is customary to admit at least a conceptual distinction between relations and the non-relational accidents in virtue of which these relations hold. The relevant non-relational accidents come to be referred to as the ‘grounds’ or ‘foundations’ of relations (fundamenta), since their possession is thought to necessitate the holding of relations. Hence, in this context, the important question is whether the distinction between relations and their foundations is merely conceptual.