The productivity of the monetary capital is the interest.
This way interest prevents full employment.
Can you elaborate on this a bit please? I think I may be confused as to what definition of the word "interest" you are using here...
I mean interest as the basic interest described by Gesell. Basically the interest of loans excluding the risk premium.
Here's how he thinks the removal of interest (by demurrage on money) would affect the labor market:
http://www.community-exchange.org/docs/Gesell/en/neo/part4/5k.htmAlthough maybe reading the whole book is needed to understand (or believe) this chapter.