 Judgements of equality presume a difference between the things compared. According to this definition, the notion of ‘complete’ or ‘absolute’ equality may be seen as problematic because it would violate the presumption of a difference. Two non-identical objects are never completely equal; they are different at least in their spatiotemporal location. If things do not differ they should not be called ‘equal’, but rather, more precisely, ‘identical’, such as the morning and the evening star. Here usage might vary. Some authors do consider absolute qualitative equality admissible as a borderline concept (Tugendhat &amp; Wolf 1983, p. 170).