 Still, anti-realists maintain that there are actual instances of conceptual schemes that explain the same phenomena equally well, schemes which, they aver, realists must judge to be logically incompatible. The earlier example of competing theories of space-time was a case in point. On one theory, \(T_1\), space-time consists of unextended spatiotemporal points and regions of space-time are sets of these points. According to the second theory, \(T_2\), space-time consists of extended spatiotemporal regions and points are logical constructions—convergent sets of regions. Realists will judge that only one of the two theories can be true if they really are logically incompatible. Anti-realists respond that the two theories \(T_1\) and \(T_2\) cannot differ in truth-value since they are descriptively equivalent. 