"Massive unemployment will shift the PPC to the left", defend or refute
We refute the statement as massive unemployment will not shift the PPC curve to left. Infact, the point on PPC where the economy was producing earlier will shift below the PPC. This is because unemployment implies inefficient use of resources and this inefficient use of resources is depicted by shifting the point below the PPC.
Note- A shift in PPC (towards right or left) will only take place if there is a change in the total endowment of the resources or in case there is a change in the production technology.