Philosophers, psychologists, and ordinary people are all interested in the pressing question: Who are you? The traditional philosophical answer, found in Plato and Kant and many religious thinkers, is that the self is an immortal soul that transcends the physical. Some philosophers who reject this metaphysical view have swung in the other direction and rejected the idea of the self altogether. David Hume said that the self is nothing more than a bundle of perceptions, and Daniel Dennett dismissed the self as merely a “center of negative gravity." In contrast, many psychologists have taken the self very seriously, and discussed at length a huge number of important phenomena including self-identity, self-esteem, self-regulation, and self-improvement. Is it possible to have a psychologically interesting view of the self that is also consistent with scientific understanding of minds and brains?
In a new article, I argue that the self is a complex system operating at four different levels. To explain more than 80 phenomena about the self, we need to look at mechanisms (interacting parts) that operate at four levels: molecular, neural, psychological, and social. Most familiar is the psychological level applying to individuals, where we can talk about self-concepts that people apply to themselves, for example thinking of themselves as being extroverted or introverted, conscientious or irresponsible, and many other dimensions of personality. Self-concepts also include other dimensions such as gender, ethnicity, and nationality. The psychological level is important, but a deeper understanding requires also considering both neural and molecular levels. At the neural level we can think of all of these concepts that people apply to themselves and others as patterns of firing in groups of neurons. A sufficiently complex account of neural representations can explain how it is that people apply concepts to themselves and others and also use them for explanatory purposes. We use concepts not only to categorize people but also to explain their behaviors, for example saying that someone did not go to a party because of being an introvert.
Moving down another level, we can look at the relevance of molecular mechanisms to understand what makes people who they are. Personality and physical makeup are affected by genetics and also by epigenetics, how inherited genes are affected by chemical attachments that may go back one or more generations. Evidence is mounting that both epigenetics and genetics are important for explaining various aspects of personality and mental illness. Also at the molecular level, understanding why people are who they are requires looking at ways in which neural operations depend on molecular processes such as the operations of neurotransmitters and hormones.
My new account of the self might sound ruthlessly reductionist, captured by some inane slogan like “you are your genes”. But in keeping with much contemporary work in social psychology, I think it's also important to appreciate the role of social mechanisms in making you who you are. Your self-concepts and behaviors all depend in part on the interactions you have with other people, including ones who influence you and also ones from whom you want to differentiate yourself. Experiments in social psychology have established that behavior depends not only on innate and learned factors, but also on situations, including people's expectations about what other people are going to do. Therefore we need to understand selves as operating at a social level, in addition to psychological, neural, and molecular levels. As Hazel Rose Marcus says, "You can’t be a self by yourself."
Hence the self is a multilevel system not simply reducible to genes or neurons, emerging from interactions of mechanisms operating at neural, psychological, and social levels. Hume was right that we cannot directly observe the self, but he was wrong in supposing that reality has to be directly observable. The self is a theoretical entity that can be hypothesized in order to explain a huge array of important psychological phenomena. The self is very different from the atomic, transcendental, perfectly autonomous self assumed by dualist philosophers, but it is far richer and more explanatory than the skeptical view of philosophers who want to dispose of the self altogether. The self does exist, but as a highly complex, multilevel system of interacting mechanisms.