Outlines • No. 1 • 2009 An Interdisciplinary Concept of Activity • Andy Blunden 1 An Interdisciplinary Concept of Activity

It is suggested that if Cultural-Historical Activity Theory (CHAT) is to fulfil its potential as an ap-proach to cultural and historical science in general, then an interdisciplinary concept of activity is needed. Such a concept of activity would provide a common foundation for all the human sciences, un-derpinning concepts of, for example, state and so-cial movement equally as, for example, learning and personality. For this is needed a clear conception of the ‘unit of analysis ’ of activity, i.e., of what consti-tutes ‘an activity’, and a clear distinction between the unit of analysis and the substance, i.e., ultimate reality underlying all the human sciences: artifact-mediated joint activity. It is claimed that the concept of ‘project collabora-tion ’ – the interaction between two or more persons in pursuit of a common objective – forms such a unit of activity, the single ‘molecule ’ in terms of which both sociological and psychological phenom-ena can be theorised. It is suggested that such a clarification of the notion of activity allows us to see how individual actions and societal activities mutually constitute one another and are each con-strued in the light of the other