“Where does the mind stop and the rest of the world begin? The question invites two standard replies. Some accept the demarcations of skin and skull, and say that what is outside the body is outside the mind. Others are impressed by arguments suggesting that the meaning of our words “just ain’t in the head”, and hold that this externalism about meaning carries over into an externalism about mind. We propose to pursue a third position. We advocate a very different sort of externalism: an active externalism, based on the active role of the environment in driving cognitive processes.” – Chalmers & Clark (1998)


In this paper, Clark and Chalmers present the idea of active externalism (similar to semantic or “content” externalism), in which objects within the environment function as a part of the mind. They argue that it is arbitrary to say that the mind is contained only within the boundaries of the skull. The separation between the mind, the body, and the environment is seen as an unprincipled distinction. Because external objects play a significant role in aiding cognitive processes, the mind and the environment act as a “coupled system”. This coupled system can be seen as a complete cognitive system of its own. In this manner, the mind is extended into the external world. The main criterion that Clark and Chalmers list for classifying the use of external objects during cognitive tasks as a part of an extended cognitive system is that the external objects must function with the same purpose as the internal processes. The authors present a thought experiment to further illustrate the environment’s role in connection to the mind.

Andy Clark is a Professor of Philosophy and Chair in Logic and Metaphysics at the University of Edinburgh in Scotland. Before this he was director of the Cognitive Science Program at Indiana University in Bloomington. Previously, he taught at Washington University at St. Louis and the University of Sussex in England.

Clark is one of the founding members of the Contact collaborative research project whose aim is to investigate the role environment plays in shaping the nature of conscious experience. Professor Clark’s papers and books deal with the philosophy of mind and he is considered a leading scientist in mind extension. He has also written extensively on connectionism, robotics, and the role and nature of mental representation.

From: 9th International Symposium of Cognition, Logic and Communication “Perception and Concepts” public opening keynote lecture by Andy Clark (University of Edinburgh, UK)

From Wikipedia: The Extended Mind hypothesis

Clark is perhaps most famous for his defence of the hypothesis of the extended mind. According to Clark, the dynamic loops through which mind and world interact are not merely instrumental. The cycle of activity that runs from brain through body and world and back again actually constitutes cognition. The mind, on this account, is not bounded by the biological organism but extends into the environment of that organism. Consider two subjects carry out a mathematical task. The first completes the task solely in her head, while the second completes the task with the assistance of paper and pencil. By Clark’s ‘parity principle’, as long as the cognitive results are the same there is no reason to count the means employed by the two subjects as different. The process of cognition in the second case involves paper and pencil, and the conception of ‘mind’ appropriate to this subject must include these environmental items.

Clark concedes that in practice the criterion of equal efficiency (required by the parity principle?) is seldom met. Nonetheless, he proposes that the boundary of ‘skin and skull’ is arbitrary and cognitively meaningless. If the paper and pencil used by the second subject becomes a virtual ‘paper and pencil’ visible on a monitor and controlled by a silicon chip implanted in the head, the similarity between the two situations becomes clearer.

Clark foresees the development of cognitive prosthetics, or electronic brain enhancements (EBEs), as only the next logical step in the human mind’s natural integration with technology. Clark’s research interests also include wetwiring and other human-electronic integration experiments, as well as technological advances in immediate human communication and their utilization in society.