cost of a product represents the total human time which has to be spent for the
production of the product, as well as for the production of all the necessary
production resources. This definition is closely related to the concept of
"value" in classical economic theory: A. Smith, D. Ricardo, K. Marx,
(see also http://en.wikipedia.org/wiki/Labor_theory_of_value). However, here we are interested
in the "social cost" as a stand-alone concept, regardless from both
the definition of "value" and the relevant theoretical debate.