Starting out from the plot of José Saramago’s novel The History of the Siege of Lisbon as well as from the notion of «error» that recurs throughout the work, particularly «the tempting error» that eventually triggers the action, this paper envisages «error» as a suitable intellectual tool to grasp the active principle of literary fiction. The set of ideas put forward in that context can be subsumed in three major planes. Firstly, we have the basic (but decisive) issue of error versus truth, namely historical truth. Secondly, the tempting error of literary fiction is studied as a form of lie, of something knowingly and deliberately false. Thirdly, and expanding on both previous planes, we defend that any contemporary reflection about the artistic word cannot ignore the uncomfortable scars which keep being carved by the tempting error into the so-called post-truth culture. We cannot blame literature alone for the configuration of the culture of lies that is being settled since the turn of the century, but literature’s culpability should not be dissociated from that culture. This is crucial not only for advancing in the understanding of literature as such but, above all, for anticipating and learning how to deal with the modalities of fictional representation that await us in the future.