To talk about nomothetism (from Greek nomos: law) refers to the methodology adopted in geographical reasoning. Inspired by the standard explanatory model acknowledged by experimental sciences, spatial analysis uses an approach of the hypothetico-deductive type. It consists in questioning reality, starting from hypotheses, and using explicitly formulated spatial theories and models. These tools are confronted with geographical reality through running simulations.
The objective of this approach is to identify regularities and explanatory principles, formulated thanks to spatial concepts, which are repeating on many parts of terrestrial space. It is realised through continuous confrontation with those general proposals and particular situations.
Bringing these rules and these general spatial mechanisms to the fore subsumes a definition of geography that is in opposition with that of a discipline conceived as a collection of places studied each in its uniqueness.
Through this ability to order the apparent complexity of phenomena, geography consolidates its scientific character.
(historical review - debate between Hawthorne and Schaefer)