For centuries philosophers and scientists have debated where the self resides. Is it in an immortal soul? Or does it instead form a part of the brain? Is the self different from the mind or the body? Or does it reside in consciousness, and, if it does, where is consciousness located? Are the mind and the body separate entities as most have supposed? These problems have bedeviled great thinkers since ancient times. And the question has still not been answered today.
The solution is simple. The self is your entire being. There is no mind/body problem. The mind, body and personality are an integrated unit constituting a being. The mind does not exist apart from the body and the body does not exist apart from the mind. We are unitary beings that act as a whole. Every individual is a self.
The self does not have a locus in the brain. There is no soul that inhabits the body. Consciousness exists as a part of our whole being. There is no need to look for it in a specific part of the brain as many misguided neuroscientists and philosophers have wasted much time in doing.
What is Self-Interest?
Self-interest is the subjectively perceived interests of the self as an entire being. Self-interest encompasses the subjective desires, needs, goals, wants, values, fears, aspirations and beliefs of a being whether they be conscious, unconscious, physical, mental, emotional or otherwise and whether they be consistent, contradictory, logical, fantastical, or utterly imaginary, all as perceived by the person in question.
Self-interest is an entirely subjective concept. It cannot be judged by an outside observer. Only the individual that experiences it has any possibility to define its own subjective self-interest. Because all perceptions are experienced internally, no being can perceive anything outside of itself. Therefore the individual is the only being that can judge what its interests are. Self-interest is expressed through internal experiences such as emotional reactions or it can be expressed by the actions of the individual in the world.
Any act of an individual is an expression of its own self-interest. And this cannot be otherwise. For individuals have no possibility other than to act based on their subjectively perceived interests. To do otherwise would be an epistemological impossibility.