The present work is a continuation of the authors' acclaimed multi-volume APractical Logic of Cognitive Systems. After having investigated the notion ofrelevance in their previous volume, Gabbay and Woods now turn to abduction. Inthis highly original approach, abduction is construed as ignorance-preservinginference, in which conjecture plays a pivotal role. Abduction is a response to acognitive target that cannot be hit on the basis of what the agent...