Montgomery and Shan (1992, 1993) have argued that in calculating resistive MHD instability thresholds, both resistivity and viscosity play an equally important role and may significantly modify conventional views of resistive MHD. The author discusses these arguments and puts them in perspective in the context of tokamak physics. The crucial point is the following: while it is indeed true that for a given q-profile, the marginal stability thresholds of linear visco-resistive MHD equations depend, in principle, upon both resistivity and viscosity jointly through the Hartmann number, physical considerations of tokamak experiments suggest that this is an insignificant modification of well known results in tearing-mode theory as far as its applications to tokamaks are concerned. Furthermore, the uniform q (equivalent resistivity) model used by Montgomery and Shan to motivate many of their arguments and to some extent their computational techniques is non-generic in a sense to be explained and is therefore not a helpful starting point for discussions of MHD stability in tokamaks. Apart from this general observation, the actual results obtained by Montgomery and co-workers regarding linear instability are all contained in the 'standard' approach used in the fusion community: specific examples are provided using the linear version of the CUTIE code developed at Culham to solve the relevant MHD equations. The CUTIE results show explicitly that JET-like tokamaks operate in a different parameter regime and involve qualitatively and quantitatively different physics to those studied by Montgomery and Shan.