  We consider a symmetric scalar theory with quartic coupling in 4-dimensions.
We show that the 4 loop 2PI calculation can be done using a renormalization
group method. The calculation involves one bare coupling constant which is
introduced at the level of the Lagrangian and is therefore conceptually simpler
than a standard 2PI calculation, which requires multiple counterterms. We
explain how our method can be used to do the corresponding calculation at the
4PI level, which cannot be done using any known method by introducing
counterterms.
