  Considerations of intelligibility certainly play a role in the debate between medieval reductive and non-reductive realists. As we shall see, non-reductive realists typically recognize that the chief difficulty for their view lies in specifying the precise nature of the sui generis monadic properties to which they appeal. More often than not, however, reductive realists object to non-reductivists on grounds of theoretical parsimony. This is certainly true in the case of Abelard and Ockham, whom we earlier identified as reductive realists. In the case of Abelard, such considerations are not explicitly formulated, though they are part-and-parcel of his general approach to metaphysics and philosophy of  language.[18]  In the case of Ockham, by contrast, the appeal to parsimony is much more explicit, often taking the form of what has come to be known as Ockham’s razor: “Plurality should not be assumed without  necessity” (Ordinatio I, d. 30, q. 2 in Opera Theologica iv, 322).