“Where does the mind stop and the rest of the world begin?” Most people might answer, “At the skull.” But Clark and Chalmers set out to convince their readers that the mind is not simply the product of the neurons in our brains, locked away behind a wall of bone. Rather, they argued that the mind is something more: a system made up of the brain plus parts of its environment.

"Eleven years later, this argument continues to trigger fierce debate among philosophers, psychologists, and neuroscientists. There is no doubt that the extended mind is a weird concept.

One reason it seems so strange is that our minds feel as if they are really totally self-contained.

We innately believe, for example, that as we walk down a street, we are continuously filming a detailed movie of our surroundings and using that mental movie to decide what to do next. But like many beliefs we have about ourselves, this movie is an illusion. Our awareness is, in fact, remarkably narrow

Clark and Chalmers have very interesting things to say. Personally, I find them very worth the effort to read. I would just add that, somewhat like the recent clip on the holographic universe, their work is quite tightly defined (which is what makes it worth following!), and the broader idea of an extended mind is a baggier and older idea. (See, for instance, McLuhan's famous remark in the 1963 Understanding Media that electronic media are and would increasingly become 'extensions of the nervous system'. I'd also recommend his lesser known work, The Gutenberg Galaxy which was, maybe still is, way ahead of its times).