There is one standard objection from the HL7 community to the position of ontological realism which underlies the commentary provided on this blog. This is that the ontological realist strives for ‘perfection’, where HL7 and its ilk, more sensibly, strive for mere ‘practical utility’.
Examination of the concrete proposals made under the ontologically realist heading prove, however, that they are (a) quite modest, and (b) of considerable practical utility.
In many respects these proposals echo the “Desiderata” advanced by Cimino. In one central respect, however, they go beyond Cimino who still (in 1998, at least) sees the way forward as lying in a move from the orientation around terms to an orientation around what he calls “concepts“. Inspection reveals, however, that the concept orientation is itself one reason for the massive inconsistencies that exist, both between different specialist terminologies, and among the different versions of these terminologies produced at successive points in time. This is because the concepts in the minds of specialists are too etherial to serve as a constraint on the builders of terminologies, for example when the latter are themselves subject to the pressures of third-party payers, gatherers of public health statistics, patient groups and other stakeholder lobbies. The result is confusion, massive waste of energy in poorly maintained mappings, ever more intensified forking, and a general failure of health IT to support, for example, continuity of care when patients move, for example, from one hospital to another or to aid in the generation of useful outcomes measurements.
The solution proposed by ontological realism — now embraced in part also by Cimino — rests on the idea that terms in ontologies (or terminologies, or messaging standards) should as far as possible be oriented, not around concepts in people’s heads, but rather around the types of entities in the corresponding domains of reality. In this respect, terminology work should mirror the practice of scientists, who use terms such as ‘electron’ or ‘planet’ or ‘mammal’ in describing their data, rather than terms such as ‘electron NOC’ or ‘planet NES’ or ‘mammal that is of interest to the human resources department’. Terms in the former group are used in remarkably stable ways, by multiple, disparate and ever expanding communities throughout the world, and there is empirical data associated with the corresponding types in reality deriving from large numbers of heterogeneous experimental sources.
The proposal is that such terms of this sort should be used in terminology resources wherever possible — not merely as terms in their own right, but also in the definitions of further terms. In this way, terminologies will be anchored — to some degree at least — to a stable, empirical benchmark, following a pattern already realized for example by the OBO Foundry ontologies. Terminology resources will also be anchored to each other, through the use of a common set of feeder terms in their respective definitions, in ways which can support consistency over time and thereby also allow the more effective aggregation of data.
We do not see this solution as a magic bullet. But we do believe that it will at least constrain forking, provide an easily generalizable strategy for the formulation of definitions, and provide other minor but significant incremental benefits.
At the same time, however, we are absolutely sure that the results which have flowed from not following this proposal are immense, and clearly visible, for example when we examine some of the problems faced by SNOMED, which has been subject to a quite remarkable number of changes in its successive versions — changes that can be attributed precisely to the concept orientation, which infects SNOMED from the top down.
I now discover that these results have been documented in a beautiful piece by Malcolm Duncan entitled “Medical terminology version control discussion paper: The chocolate teapot (Version 2.3)” in relation to the Systematized Nomenclature of Kitchen Terminology (SNoKitch), and specifically to the two non-contiguous branches Crockery and Teamaking Related Findings in its n.3 release:
—– Brown teapot
———-White china teapot
———-Blue china teapot
———White china teapot
———Blue china teapot
Tea making related findings—Teapot related findings——Large teapot——Full teapot——Empty teapot——Teapot with warm water——Teapot with cold water.
The document in question is cited in a (long) HL7 discussion concerning the problems which arise in connection with the Cimino desideratum of “concept persistence”. This discussion, incidentally, reveals one flaw in Cimino’s formulation of his desiderata: for it shows that recommending “concept persistence” as a desideratum is a bit like recommending “life persistence” for the patients in your hospital. Life persistence is, certainly, a nice thing; but it would be even better, surely, if one can formulate a desideratum which identifies some specific strategy for achieving it — in such a way that the desideratum of persistence will follow as by-product. It is something like this which ontological realism, in its stumbling fashion, is attempting to do.