  So far we have argued that demonstrative identification is not reducible to descriptive identification. But Strawson makes the stronger claim that, in the reduplication universe, descriptive identification depends on demonstrative identification. To get this stronger claim consider an object that Sally has never perceived but can intuitively think about — say, Bill's mother. Strawson claims that considering this case proves false the claim “that where the particular to be identified cannot be directly located [i.e., cannot be demonstratively identified because it cannot be perceptually discriminated], its identification must rest ultimately on description in purely general [i.e., qualitative] terms” (1959, 21). Bill's mother (call her Morgan) is qualitatively indiscernible from Bill*'s mother. So Sally is unable to distinguish in purely qualitative terms Morgan from every other object in the universe. But intuitively she can nonetheless think of her. This is because Sally can demonstratively identify Bill and thus have thoughts determinately about Bill as opposed to his qualitative twin Bill* and then think of Morgan under the descriptive condition Bill's mother. As Bill is directly given, this is a condition that Morgan and not her qualitative twin Morgan* satisfies. Thus Sally's ability to descriptively identify objects in the universe is ultimately grounded in her ability to demonstrative identify some stock of objects, identifying other objects in virtue of the unique relations they bear to members of that stock. Strawson argues that the general way of relating objects one has not perceived to those demonstratively identified is by way of spatio-temporal relations. (See (1959, 22) in particular, but much of the discussion that follows in chapter 1 is aimed at establishing the Kantian claim that spatio-temporal relations are the privileged set of relations for enabling identification of particulars.)