  The availability of the double-differential charged-current neutrino cross
section, measured by the MiniBooNE collaboration using a carbon target, allows
for a systematic comparison of nuclear effects in quasi-elastic electron and
neutrino scattering. The results of theoretical studies based on the impulse
approximation scheme and state-of-the-art models of the nuclear spectral
functions suggest that the electron cross section and the flux averaged
neutrino cross sections corresponding to the same target and seemingly
comparable kinematical conditions can not be described within the same
theoretical scheme using the value ofthe nucleon axial mass obtained from
deuterium measurements. I analyze the assumptions underlying the treatment of
electron scattering data, and argue that the development of a new {\em
paradigm}, suitable for application to processes in which the lepton kinematics
is not fully determined, will be required.
