The mind as a complex system
Brains and bodies are obvious examples of things – physical entities or objects. Like other paradigmatic physical objects, they have stable spatial boundaries and a host of other properties such as mass, density, and internal composition and organization. But are minds, or the ideas that fill them, also things? Are they object-like in these ways? Cartesian substance dualism, while it denied that the mind was something physical, nevertheless took it to be a kind of object or entity. Descartes argued further that the mind was not only a nonphysical object, but that it was also an indivisible object: it could not be decomposed into parts in any way whatsoever.
Ontologically, minds are systems, and some systems can also be object-like or entity-like. Atoms, solar systems, biological organisms, and hurricanes are all examples of entity-like systems. As systems they are decomposable into component parts and operations, but like many objects, they are also relatively persistent, coherent, and spatially circumscribed. Given the complex psychological and behavioral phenomena they give rise to, minds must be systems of extreme complexity. Like other complex systems, they have an internal design plan. For artificial computing devices, this plan corresponds to their circuit diagram – the description of their central processors (e.g., their instruction set), memory, system bus, various sub-controllers for storage, networking, audiovisual output, and so on. For biological organisms, this plan corresponds to their overall anatomical organization, their breakdown into organ systems (circulatory system, respiratory system, immune system), into individual organs and other active components (airway, lungs, diaphragm, etc.), and still further into specific types of specialized sub-organs, tissue and cell types, secretions and fluids, and so on.