The Structural Realist theory of the Self (SRS) is presented as an extension of structural realism in the philosophy of many-particle physics. Structural realism addresses the problem of conflicting ontological consequences with regards to the existence of individual objects at the sub-particle level by making commitments to commonalities. In the same way, SRS endorses epistemological and ontological commitments to the underpinning informational structure of the self. This is a neat way of overcoming the state of underdetermination in the field of neuroscience of selfhood. And there is such a state of underdetermination (aka pluralism) in the field of cognitive science (for discussion see chapter three). Eliminativism about the self, the pattern theory of self, the cortical midline structure theory are only some of the important scientifically-informed theories of the self that come to mind. SRS claims that it is possible to be realist with regard to the commonality or the common informational structure that subsumes various aspects and elements of the self (or self-models, in the case of the eliminativist accounts). None of these views provides a viable alternative to substantivalism though, and yet all of them seem to be correct at the same time. The self-structure provides a scaffolding for relating diverse aspects and elements of the self without giving way to substantivalism (either in its Cartesian guise or modern version that is defended by P.F. Strawson). And the scaffolding could be a subject of realist commitments. Unlike substantivalism, SRS is compatible with recent breakthroughs in cognitive psychology and draws on them to reconceptualise the self as a structural object. But the question is how to specify the self-structure. I suggest that it is possible to specify the self-structure at both neurological and information-theoretic level. Chapters four and five provide the requisite technical details.
At the neurological level, the self-structure is composed of a coupled dynamical system, consisting of the cortical midline structures (CMS) and the mirror neuron system (MNS). CMS is a part of the Default Mode Network, and it provides a base for the activity of the resting state of the brain. MNS includes multimodal motor neurons that populate ventral premotor areas and the inferior parietal lobe of the brain. There is experimental evidence that both CMS and MNS engage in processing of both personal and social aspects of the self. More than that, there is evidence that CMS and MNS collaborate in realizing the personal and social aspects of the self. In other words, CMS and the MNS collaborate in underpinning the embodied informational structure of the self, which is a subject of ontological commitments.
Alternatively, the self-structure could be specified in terms of the Free Energy Principle (FEP). According to Karl Friston, FEP provides a grand unifying framework for grounding (approximate Bayesian) optimization. It explains that in order to remain in the state of equilibrium with the environment, organisms must minimize their free energy. Minimizing free energy is tantamount to maximizing survival and the theory could account for the organisms’ rather reliable knowledge (or perception) of the world. The book offers expansive technical explication (in chapters four and five) but the take-home-point is that as Apps & Tsakiris (2014) and Limanowski & Blankenburg (2013) argue, FEP could specify mechanisms of multisensory integration of self-related (visual, tactile, proprioceptive) stimuli. FEP could explain how it is that the self has a rather precise representation of its own body because in order to minimize its free energy successfully, the agent must place itself in regions of the environment that are most predictable and this provides a probabilistic basis for accounting for the mental representation of the self and its embodied properties in terms of the congruent corollary discharge, vestibular, somatosensory, and interoceptive information (see chapter 4, pp.141-42). The book argues that the self-structure could be specified in terms of the Bayesian framework that is offered by FEP.
In short, the scaffolding of self-structure can be specified in terms of the coupled system consisting of CMS-MNS (at the neurological level) and FEP (at a higher level of representation). There are both formal and theoretical links between FEP and the mentioned coupled system. And it is important to note that the self-structure is not secluded from its ecological or social environment. Not only there is a dynamical relation between the self and its environment and its social web, but also the self is extended to the world and self-structure and environmental and social structures are coupled. In the next section, I explain how phenomenal, social, and also ethical aspects of the self too could be specified along the lines of SRS.