The Logic of Identity and Copy for Computational Artefacts Nicola Angius Department of History, Human Sciences, and Education University of Sassari, Italy nangius@uniss.it Giuseppe Primiero Department of Computer Science Middlesex University, London, UK g.primiero@mdx.ac.uk Abstract Defining identity for entities is a longstanding logical problem in philosophy, and it has resurfaced in current investigations within the philosophy of technology. The problem has not yet been explored for the philosophy of information, and of Com- puter Science in particular. This paper provides a logical analysis of identity and copy for computational artefacts. Identity is here understood as the relation holding between an instance of a computational artefact and itself. By contrast, the copy relation holds between two distinct computational artefacts. We distinguish among exact, inexact and approximate copies. We use process algebra to provide suitable formal definitions of these relations, using in particular the notion of bisimulation to define identity and exact copies, and simulation for inexact and approximate copies. Equivalence is unproblematic for identical computational artefacts at each individual time and for inexact copies; we will examine to which extent the for- mal constraints on identity criteria discussed in the literature are satisfied by our approach. As for inexact and approximate copy, they are intended as a weakening of the identity relation in that equivalence and other constraints on identity are vi- olated. The proposed approach also suggests a computable treatment of identity and copy checking. Keywords. Philosophy of Information; Philosophy of Computer Science; Identity Cri- teria; Copy; Process Algebra. 1 Introduction Since Frege, the problem of identity of the informational content of two sentences is a fundamental one in the philosophy of language and information. The more recent debate in the philosophy of technology has exploited this problem for the analysis of 1