Human intelligence requires inhabiting a human body (including one's internal feelings) and living in a human world.
It all seems very complicated but I actually take the opposite view to Marco's 'embedded behaviourist' view on this. I think what is needed is to work out exactly where in the brain these various aspects, like awareness, motivation, reflex response, and rational decision making occur and to work out which illnesses relate to which bit or to none of them.
I think both views are right, they are like two side of the same coin.
Let me start by giving a few of my rules of thumb:
1. To understand something you need both the big picture and the fine details. The big picture without the details is a house of cards. The details without the big picture will be used unwisely. In military terms a fine detail thinker is a tactician, a big picture person is a strategist, going into war without both is a mistake. You might only need a few big picture thinkers to a lot of fine detail thinkers, but you still need them.
2. A corollary to the big picture rule is that if you want to change something, you need to understand the details of everything it changes in turn, or risk unintended consequences. This includes feedback loops which are very resistant to conventional reasoning. How many drugs have been developed in which the associated pathways affected were never adequately investigated?
3. The difficulty with big picture thinking is that there are no boundaries and no limits. Boundaries are purely for pragmatic reasons.
I don't think we can really understand the mind without considering the brain as an embedded system. However I also think we need to understand all the mechanisms. Then we need to understand how they combine, under what conditions, what changes etc. etc. The human brain is one of the most complex things we have ever tried to figure out.
Changes in the brain are as a result of both internal mechanisms and interaction with the world.
I would like to introduce a term from the early days of systems biology, one used by Maturana and Verela - "structural coupling". In evolutionary terms, systems that survive in an environment survive because they is congruency between how the system works and the environment it is in, congruency which enhances survival unless the environment changes. There is a coupling between brain and environment, and the structure of the brain reflects that. Human environments include not only the natural world but a social one
In case there is any doubt, I think the base notion of BPS is sound, but it was deliberately and systematically used to justify psychosomatic medicine from Engel's first paper and even before. From a sound basis he created a house of cards.
Structural coupling is actually an essential notion in systems evolutionary biology. Biological species don't just evolve, they evolve in an environment with other species that are evolving. Humans have two additional layers to that, language and culture.
My best guess is that what we call mind arises out of many mechanisms with complex discriminatory and feedback loops, and that conventional isolate and test can only go so far. Yet if we don't understand how the bits work, how can we figure out the big picture?