  The standard MS renormalization prescription is inadequate for dealing with
multiscale problems. To illustrate this, we consider the computation of the
effective potential in the Higgs-Yukawa model. It is argued that the most
natural way to deal with this problem is to introduce a 2-scale renormalization
group. We review various ways of implementing this idea and consider to what
extent they fit in with the notion of heavy particle decoupling.
