This is a pre-copyedited, author-produced PDF of an article accepted for publication in Journal of Logic and Computation following peer review. The definitive publisher-authenticated version Caminada, MWA, Dvořák, W & Vesic, S 2014, 'Preferred Semantics as Socratic Discussion' Journal of Logic and Computation is available online at http://logcom.oxfordjournals.org/content/early/2014/02/06/logcom