A boundary between the “self” and the “outside world”
In case of a space probe, it is relatively easy to draw a boundary between the probe which is being controlled and the person doing the controlling. However, if this analogy is used to describe what is happening within a person then things become much more hazy.
For instance, it is generally believed that the locus of consciousness is in, or at least associated with, the brain. Therefore, arms and legs, together with the sensors and muscles which they contain, could be seen as being part of the external systems which are being controlled by the brain rather than part of the essential individual.
That this is widely intuited is demonstrated by the observation that most people would not imagine that replacing a leg with a prosthetic one would change their character or in some other way make them a different person.
Similarly, if someone is given an organ transplant, whether it be a heart or a limb, few would consider them to be a different person from who they were before the transplant took place.
The limb or the heart is considered as part of the equipment with which we are endowed which allows us to survive and operate within the Earth’s environment in a directly analogous way to the space probe giving such capabilities to the operator.
However, suppose we try to move the boundary further towards the brain and maybe into the brain itself. As we do so, we initially find a large number of unconscious and autonomous systems which are able to respond to sensory inputs in a way which, hopefully, aids survival and efficiency.
Are these systems part of the person or are they part of the associated machinery? Would replacing a part of the brain with an artificial substitute or a transplant change who the person is? If so, which parts of the brain would cause this effect? A retina? An optic nerve? The V1 visual centre?
Is the person responsible for what these unconscious systems do any more than they are responsible for what the heart does? Or what their cerebellum does?
If our freedom to choose is limited, how does this reflect on culpability and personal responsibility? Where does our autopilot stop and the real “me” start? If we keep stripping off the non-conscious processing will there be anything left?
Many people speak of the person as being more than a monolithic entity. For instance, Plato, in one of his dialogues says this [1]:
St. Paul also speaks of the “higher” and “lower” nature or the “spirit” and the “flesh”. eg. Romans 8.
Another reference to our having two natures is given in the story of the two wolves, attributed to the Cherokee[2].
A similar perspective is described from the psychological point of view in a book which investigates “self-control” and “grit” [3].
[1] Plato, “The Republic”
[2] http://www.firstpeople.us/FP-
[3] Walter Mischal, “The Marshmellow Test”