In capital III as Mike points out Marx explicitly restricts
himself to the study of landed property within the capitalist
mode of production. He makes the simplifying assumption that
agriculture is dominated by the capitalist mode of production.
Within a book on Capital this is a rational assumption, but
would the same apply to a book on landed property per-se?
We have to take into account the fact that both at the time
Marx was writing, and today in a large part of the world
economy, agriculture is not dominated by capitalist relations
of production. If we were simply to assume that it was, our
analysis would be incapable of dealing with many of the
most significant developments of 20th century history.
Landed property, and the landlord class that is based upon it,
have been and remain major influences on economics and
politics. There existence can not be deduced from the
categories of capital, but have their own synchronic and
diachronic supports.
Modern society, understood as the world today, incorporates
a number of coexisting systems of social relations deriving
from both capitalist and pre-capitalist modes of production.
Modern society is not reducible to capitalism.