This was what philosophers Andy Clark and David J. Chalmers asked in their 1998 thesis, The Extended Mind: “Where does the mind stop and the rest of the world begin? (…) Some accept the demarcations of skin and skull, and say that what is outside the body is outside the mind.” In this scenario, we use our senses to gather information which is sifted through our mind to produce our perception of reality, us being a bystander of the world. Rather than limiting the mind to the physical boundaries of the body, the paper argues that the mind is made up of its cognition and its body’s immediate environment. It says the environment plays an active part in the cognitive process as an extension of the mind - the mind stretching out of the body and including the world in itself.

To clarify, Clark and Chalmers put forth an example of the extended mind, situating the concept in practical terms:

Inga hears from a friend that there is an exhibition at the Museum of Modern Art, and decides to go see it. She thinks for a moment and recalls that the museum is on 53rd Street, so she walks to 53rd Street and goes into the museum. It seems clear that Inga believes that the museum is on 53rd Street, and that (…) the belief was sitting somewhere in memory, waiting to be accessed.

Now consider Otto. Otto suffers from Alzheimer’s disease, and like many Alzheimer’s patients, he relies on information in the environment to help structure his life. Otto carries a notebook around with him everywhere he goes. When he learns new information, he writes it down. When he needs some old information, he looks it up. For Otto, his notebook plays the role usually played by a biological memory. Today, Otto hears about the exhibition at the Museum of Modern Art, and decides to go see it. He consults the notebook, which says that the museum is on 53rd Street, so he walks to 53rd Street and goes into the museum.

Clearly, Otto walked to 53rd Street because he wanted to go to the museum and he believed the museum was on 53rd Street. (…) [In] relevant respects the cases are entirely analogous: the notebook plays for Otto the same role that memory plays for Inga. The information in the notebook functions just like the information constituting an ordinary non-occurrent belief; it just happens that this information lies beyond the skin.