 A noteworthy feature of abduction, which it shares with induction but not with deduction, is that it violates monotonicity, meaning that it may be possible to infer abductively certain conclusions from a subset of a set S of premises which cannot be inferred abductively from S as a whole. For instance, adding the premise that Tim and Harry are former business partners who still have some financial matters to discuss, to the premises that they had a terrible row some time ago and that they were just seen jogging together may no longer warrant you to infer that they are friends again, even if—let us suppose—the last two premises alone do warrant that inference. The reason is that what counts as the best explanation of Tim and Harry’s jogging together in light of the original premises may no longer do so once the information has been added that they are former business partners with financial matters to discuss.