Ideology biases information processing, particularly evaluation of the content of political messages. We investigated whether ideology can even bias evaluation of the logical quality of arguments. 1681 participants read four arguments about different political topics and rated the extent to which they agreed with the conclusion, and the extent to which the argument was sound - that the conclusion followed from the premises. Each participant received sound liberal, unsound liberal, sound conservative, and unsound conservative arguments. Participants effectively distinguished sound from unsound arguments, but this was qualified by the ideology of the argument. Specifically, liberals found sound and unsound liberal arguments more sound than sound (η2 =0.18) and unsound (η2 =0.13) conservative arguments respectively. Likewise, conservatives found sound and unsound conservative arguments somewhat more sound than sound (η2 =0.05) and unsound (η2 =0.12) liberal arguments respectively. Ideology affects the evaluation of political arguments, even recognition of its logical merit. -- Anup Gampa Doctoral Student Critical Psychology University of Virginia anup@virginia.edu 937.367.1334 "Stop acting so small. You are the Universe in ecstatic motion." Rumi