Prediction is Deduction but Explanation is Abduction

Abstract

This P~I>t:r p~esents ru:t approach to te.mP?ral reasoning in wh1ch predicnon 1s deductlon but explanatlon 1s abduction. It is argued that all causal laws should be expressed in the natural form effect if cause. Any given set of laws expressed in this way can be used for both forwards projection (prediction) and backwards projection (explanation), but abduction must be used for explanation whilst deduction is used for prediction. The approach described uses a shortened form of Kowalski and Sergot'~ Event Calculus and incorporates the assumption that propert1es known to hold must have explanations in terms of events. Using abduction to implement this assumption results in a f~rm of default persistence which correctly handles problems wh1ch have troubled other formulations. A straightforward extension to SLD resolution is described which implements the abductive approach to explanation, and which complements the well-understood deductive methods for prediction.