Economic Logic with Internal Consistency (and Not Only Formal Rigour). Realism and Internal Consistency in Piero Sraffa

As is well known, during his life Sraffa never published a work explicitly devoted to epistemological issues. This fact should not be interpreted to indicate Sraffa’s lack of interest in such concerns. From Sraffa’s unpublished manuscripts – kept at the Wren Library of Trinity College, Cambridge, and from the books of his personal library – we see that Sraffa had a strong interest in questions of philosophy of 8science (Kurz and Salvadori, 2005). Therefore, a reconstruction of Sraffa’s epistemological theory can only be conjectural and must not leave out of consideration his unpublished manuscripts. In a previous work (Salvadori and Signorino, 2007), we analysed a specific aspect of Sraffa’s epistemology, the threefold relationship between ‘economic reality’, ‘the economist’ and ‘economic theory’, and we focused almost exclusively on the published material and used unpublished manuscripts only sparingly to show that our statements based on the published contributions were confirmed by, or at least consistent with, the unpublished material. In this chapter, we shift our attention to a somewhat related theme, the relevance of the realism of the premises in the assessment of a theory, and we make extensive use of unpublished manuscripts, while being aware of the necessary caution in using material that an author has not published. (Caution is even more significant in the case of an author such as Sraffa who is particularly careful with his choice of words and extremely reluctant to publish anything except after a long period of reflection.) u