Nature - autonomous learning

the dis/unity of geography 197of the Rhine’s sediment-carry characteristics help us to understandthe unifying principles controlling the sediment loads of the RiverExe, the River Rhine and the Amazon river’ (Favis-Mortlock andde Boer, 2004: 164). A deductive-nomological explanation takes thefollowing form:L1, L2...Ln (Laws, theories and models)T1, T2 . . . TnM1, M2...Mn+C1, C2...Cn (Initial conditions)E(Past, present or future event/s)Here, a set of empirical events can necessarily be described, explainedand/or predicted from a set of well-confirmed laws, theories ormodels coupled with factual information about the local conditionsprevailing at the site where the explanation or prediction applies. Forinstance, if a hydrologist has a set of general laws about soil porosityand water throughflow, plus information about the local soil type andits antecedent moisture content, they might be able to both explainand predict why and whether overland flow occurs during a particularrainstorm as opposed to subsurface flow. In physical geography, itis frequently the case that deductive-nomological explanation takesa probabilistic rather than strictly deterministic form because of theopen-systems nature of the biophysical world. What’s more, inpractice deductive reasoning is bound up with deductive andabductive reasoning (see Box 4.5 for a discussion of the latter).The deductive-nomological form of explanation is usually equatedwith a positivist view of science. Physical geography is often consideredto be positivist (and human geography was once positivistaccording to some). But in my view this label has become meaninglessthrough overuse. The term lacks clarity of meaning becauseit has been used indiscriminately in the literature over the years.