  For decades following its introduction in 1968, the resistively and
capacitively shunted junction (RCSJ) model, sometimes referred to as the
Stewart-McCumber model, was successfully applied to study the dynamics of
Josephson junctions embedded in a variety of superconducting circuits. In 1980
a theoretical conjecture by A.J. Leggett suggested a possible new and quite
different behavior for Josephson junctions at very low temperatures. A number
of experiments seemed to confirm this prediction and soon it was taken as a
given that junctions at tens of millikelvins should be regarded as macroscopic
quantum entities. As such, they would possess discrete levels in their
effective potential wells, and would escape from those wells (with the
appearance of a finite junction voltage) via a macroscopic quantum tunneling
process. A zeal to pursue this new physics led to a virtual abandonment of the
RCSJ model in this low temperature regime. In this paper we consider a
selection of essentially prototypical experiments that were carried out with
the intention of confirming aspects of anticipated macroscopic quantum behavior
in Josephson junctions. We address two questions: (1) How successful is the
non-quantum theory (RCSJ model) in replicating those experiments? (2) How
strong is the evidence that data from these same experiments does indeed
reflect macroscopic quantum behavior?
