 Hybrid theories of health and disease attempt to overcome the gaps in both the naturalistic and normative approaches, by hybridizing aspects of both theories (Reznek 1987; Wakefield 1992; Caplan 1992). For instance Jerome Wakefield (1992, 1996, 2007), writing about psychiatric conditions in particular, notes that a condition should be considered a disease if it both causes harm to the person or otherwise contributes diminished value, and the condition results from some internal mechanism failing to perform its natural function (hence for instance much of what is diagnosed as “depression” would fail to count as a disease condition). Whereas the normativist is committed to calling any undesirable state a disease condition, these hybrid criteria rule out calling conditions “diseases” which are non-biological,. Then various marginal cases might be considered to be healthy rather than potentially described as diseased, and hence might not be eligible for treatment within conventional medicine. Examples include those organs or structures that no longer have a function due to evolutionary processes cannot malfunction and so cannot be diseased. Many hybrid approaches also retain too many assumptions about their naturalistic components, and hence are criticized for relying on a notion of natural function which cannot be supported by biology.