<cite>Webber et al. (2003)</cite> observe that identification of the correct antecedent of a definite description such as the tower or this tower in (12a) or a discourse adverbial such as otherwise in (12b) may require reference to abstract discourse objects such as the result of stacking blocks (to form a tower) or the state of not wanting an apple as the logical antecedent of a definite description or of a discourse adverbial.