 Many criticisms have been raised against both the original Nagel model and its variants. The original Nagel model was faulted as too narrow because it allows only for theory reduction (Wimsatt 1972; Hull 1976; Darden &amp; Maull 1977: 43; Sarkar 1992), whereas an appropriate model would cover cases of reduction of mere models and the like—sciences like biology and neuroscience should be regarded as being possible candidates for reduction, although they do not contain full-fledged theories (see also the entry on  reductionism in biology;  for a discussion of this and the following criticisms, see van Riel 2011).