Fundamental Objections to the 7th Approximation

Summary The 7th Approximation suffers from three fundamental ills. It demands an unattainable degree of precision and its exactly defined, mutually exclusive classes lead to inconsistency or absurdity when the system is used. Logical division is used out of context to construct a hierarchical structure, while the dispersed nature of soil distribution does not lend itself to hierarchical arrangement in any form. Its search for genetically significant properties on which to define classes involves circular reasoning, since the genetic significance of a property can usually be discovered only after the soils have been classified. Mutual exclusion and rigid adherence to the hierarchy result in the system failing to serve adequately the requirements of soil survey. The 7th Approximation explores to the limit the potential of logical division for soil classification yet remains unsatisfactory. The nature of soil distribution and the requirements demanded of soil classification suggest that a co‐ordinate system would be more profitable, and a study of such systems is urged.