The purpose of the paper is to discuss the kind of objectivity which allows Sraffa to deal with two different economies, one without and the other with a surplus product.

Whether it makes or it does not make sense to take the technique as being physically given (i.e. observable from a "man fallen from the moon") is at the heart of the matter.

It is shown that the only relevant objectivity is not physical but social. What is called 'technique' crucially depends on the social conditions of production. Two propositions are demonstrated: (i) in Sraffa's framework, if market prices are equal to natural prices, any market economy where all producers are independent has zero surplus product (ii) A surplus product may be objectively observed only if workers are wage-earners working for entrepreneurs.

Better than 'techniques' or 'physical commodities', monetary relations objectively reveal the crucial difference between a simple market economy and a market economy with surplus. A brief illustration is provided.

INTERNATIONAL CONFERENCE sponsored by Department of Economics Faculty of Economics University of Bergamo THE OTHER SRAFFA. SURPRISES IN THE ARCHIVE? December 21-22, 2010 aula 3, via Salvecchio 19 University of Bergamo - Bergamo Alta, Italy