Therefore if we are the complete products of nature/nurture and have no ability to venture outside that definition, then arguably our entire existence is deterministic (at least as far as our mental facilities are concerned). However, this also makes me consider whether this isn't unnecessarily reductionist.
In reductionism, it is useful to take anything which exhibits complexity and break it down into constituent parts or processes to gain a better understanding of what is occurring. This approach provides a means whereby a problem can be broken down into smaller and smaller pieces to gain insight into whatever is being studied. The hazards of this viewpoint are that, while it may provide a useful perspective, it may become a vehicle for extrapolating conclusions that simply aren't true. Understanding a part of a process is not synonymous with understanding the process itself.
The concept of emergent properties recognizes that the object being examined isn't necessarily the simple sum of its parts, but may have characteristics that don't exist until all of its components are put together. In effect, the whole is greater than the sum of its parts.
As an example let me resort to a computer analogy, since this is a reasonable example of something that is capable of being reduced and being necessarily deterministic. In addition, because of its familiarity to many people, there is a strong temptation to take this knowledge and draw comparisons to other systems that seem to reflect similar behaviors (i.e. computer programs and DNA), which can lead to many gross misinterpretations.
In a computer system, one can look at a system and see that it can be broken down into smaller and smaller components, such as applications, programs, instructions, etc. Each level down brings us closer to seeing how the individual parts work, until we are ultimately looking at the actual one's and zero's that make up the representation of data/instructions in the computer itself. This is where the problems can begin if one doesn't choose the framework carefully. While one can examine a system down to the level of one's and zero's, one cannot extrapolate the system from one's and zero's. At some point this becomes too reductionist and we become bogged down with unnecessary details that can lead us to erroneous conclusions about the phenomenon being examined. So as we begin to see that the one's and zero's represent data and instructions, and then examine how these collection of instructions can be grouped together to form programs, we see the emergence of a "behavior" that extends beyond the simple representations we viewed initially.
Specifically, we find that the particular use to which a program is put may extend well outside the original design parameters and lead to "behavior" that could never be anticipated by examining the components only. So what we have is a system that is based on the simple use of one's and zero's and yet can show "behavior" as diverse as this document, telecommunications, or rendering fantasy characters (CGI) in movies.
At some point, we must recognize that having a completely deterministic system, like a computer, can give rise to many "behaviors" that have nothing to do with the limitations of the constituent parts.
This parallels the discussion regarding "free will" and considerations of the role genetics and biochemistry play in the brain. An important question to consider is that if restricting computers to one's and zero's or restricting atoms to protons, neutrons, and electrons has not limited the diversity to which these combinations can give rise, is it necessarily a foregone conclusion that the biochemistry that produced and controls the brain is any more limiting?
In particular when it comes to considering the degree of freedom the brain has regarding its electro-chemical actions, the question could be rephrased to consider whether it is the brain's chemistry that determines what occurs, or that it is the actions of the organism that determine the chemistry. In our computer analogy that question would ask if it was the one's and zero's that determine what the system can do, or is it the system that determines what the one's and zero's will be?
Invariably from a reductionist perspective it is easy to fall into the trap to say that the system doesn't exist without the one's and zero's and therefore they must be the determining factor, but in truth, it isn't the one's and zero's that give rise to the system either. It is the emergent property of all these items together that gives rise to something that is more than either one is separately.
Similarly in considering the effect of brain chemistry, we can argue that it is only the collective actions of the entire organ (and organism) that can determine the state of the brain, and that there is no meaningful question that can be asked regarding a single trigger.
"We behave well because social good behaviour fires off pleasant neurochemicals in our brains (the pleasure reward), because consciously or unconsciously we want others to see us as a good person (the social reward) or to feel good about ourselves (for pride and self-esteem)."However on closer examination this statement is meaningless because it suggests that there is some mechanism in the brain that "understands" goodness and therefore rewards that behavior when the external organism exhibits it. Similarly, how would one credit the genes with creating such a reward system without being forced to conclude that the gene itself is capable of distinguishing between good and bad.
"Altruism is an Illusion" by Vexen Crabtree, 2006 Jan
Perhaps the "reward" that we're seeing is derived from external behaviors and not interally at all? Consider that at the simplest levels, our biological systems have a "fight or flight" mechanism that involves adrenaline and other chemical reactions to prime the body for some confrontation. Ignoring all the evolutionary steps that created such a system, we'll simply acknowledge that it is there and consider how a "reward" system may have come about in terms of how it is expressed in the brain response.
I'm sure everyone has experienced the situation where they experience an increase in tension, which is the body priming itself for some event to occur. If we discover that it is nothing to be concerned about, then we will generally notice a sense of relief. Depending on the degree of tension/relief felt, it isn't difficult to see how the feeling of relief could become a "reward" sensation. From this, we may experience similar chemical reactions if we find that encounters with others resulted in "relief" that no confrontation occurred, so over time, we are creating the brain chemistry to associate the lack of a confrontation with the "reward" feeling.
I want to be clear that I'm not offering an evolutionary explanation for the brain, nor it's chemistry. I'm only trying to show that it is possible that the brain chemistry necessary to exhibit a pleasant "reward" sensation could have derived from nothing more than the relief at not having to run or fight. In effect, then the organism is what would've driven the brain chemistry and not the other way around. This could have developed into an internal control system that eventually caused some organisms to recognize that cooperation was easier than confrontation, so that those that experienced that "reward" sensation tended to cooperate more (potentially giving rise to even fewer conflicts with outside organisms).
In effect, what this process describes is that the brain's chemistry would've "learned" that a particular behavior was more beneficial than a contrary behavior. A phenomenon not fundamentally different than the outside pressure we exert on our brain in learning how to read. Similarly, it is clear that it is the organism itself that exerts control over the brain in setting the various electro-chemical states to achieve learning and retain memories. Therefore, we are forced to conclude that whatever the behavior of the brain is, it is not being generated internally, but rather it is being formed by external actions. In other words, the brain cannot be induced to read or do arithmetic, it must be externally conditioned to respond and perform those tasks. So while the genes and biochemistry dictate the framework around which this occurs, like our computer system, this isn't a limitation, but rather it is simply a particular architectural implementation.
To put this into the context of free will, this would seem to suggest that we aren't merely the hapless victims of a brain's chemistry that is dictated by our genes, but rather our genes are responsible for creating a working environment into which we exert a great deal of influence. We will clearly be influenced by those that teach us, and that provide us our viewpoint and belief systems, but primarily we recognize that it is the outside world that shapes our brain's operation (absent anatomical or physiological defects). It has also been argued that it is our indoctrination that affects free will, however, this argument begs the question because it really suggests that our indoctrination was taught rather than deterministically set. Therefore, if it was taught, then other things can be taught as well, so it really is an indication that the flexibility exists within the brain's architecture and while it may exert a powerful influence on our behavior, it doesn't exclude being changed.
This would then suggest that there is free will present in the human brain, however, it should also be considered that "free will" doesn't automatically mean that changing our "minds" is a trivially easy task to accomplish. Regardless of such difficulties, it seems that our brain/mind behavior is not completely deterministic, and therefore "free will" does exist.