Abstract. We associate optimality theory with abduction and preference handling. We present linguistic problems that appear in the study of dialects as new application of abduction and preference handling. Differences in German dialects originate from different rankings of linguistic constraints which determine the well-formedness of expressions within a language. We introduce a framework for analyzing differences in German dialects by abduction of preferences. More precisely, we will take the perspective of a linguist and reconstruct dialectal variation as abduction problem: Given an observation that a sentence is found as grammatically correct, abduct the underlying constraint ranking. For this, we give a new definition for the determination of optimal candidates for total orders with indifferences. Additionally, we give an encoding for the diagnosis front-end of the DLV system.