When might human indexing be strongly justified

The paper is concerned with the justification for human indexing, in the modern era. We understand human indexing in a classic sense, of human description of information objects in accord with a controlled vocabulary.

A justification for human indexing would be, when it yields a value commensurate with its cost. A long historically established value for retrieval systems is selection power, or an enhanced capacity for informed choice for the searcher.

The question of the justification for human indexing is made analytically tractable by reversing the historical order of development. We ask, what forms of selection power are not readily obtainable from human use of computationally generated selection processes in searching?

Selection processes widely available for searching written documents, for words, phrases, and combinations of words and phrases, are reviewed in ascending order of creativity.

Human indexing is strongly justified, when the exchange value involved in producing its use value (likely to be realized as generic power) are commensurate with the exchange value it can command.

The argument is conducted with written documents as examples but the possibility of extension of its conclusion to non-written documents is indicated.