Last week, the Nobel Laureate Eric Kandel reported in the NY Times on positive developments in the neuropsychiatry of depression, specifically citing the work of Dr. Helen Mayberg, who has increased our understanding of some of the major brain areas that tend to be associated with clinical depression. A particularly interesting and encouraging aspect of her work is the finding that there may be different patterns of brain activity that may lead to different treatment recommendations. Kandel’s overarching point in the article is that the biology of mental disorders is advancing, such that we now know that “mental disorders are biological in nature, [and] that people are not responsible for having schizophrenia or depression.” Not surprisingly, Dr. Kandel’s claims elicited many replies, several of which challenged or raised question about what might be considered biological reductionism.

Dr. Kandel’s piece and the replies remind us just how complicated and confusing the connection between biological and psychological and social processes can be, and how, if we don’t have a good map, things get very complicated very fast. My goal here is to show how to think clearly about the relationship between the various dimensions of complexity in nature and to apply the model to clear up the confusion about the “true” nature of depression. I argue we should be thinking of depression as a state of psychological shutdown that can then be broken down into depressive reactions, depressive disorders, and depressive diseases (also see here and here for more on the best way to think about mental disorders). To get to this conclusion, though, we need a bit of background on how to think about the dimensions of complexity in nature.

Let’s start with Dr. Kandel’s assertion that because mental disorders are biological, then people are not responsible for them. Is this a legitimate assertion? The answer is yes and no because it depends on what is meant by “biological”. To be clear about the potentially confusing nature of the issues, it is important to understand that there are dimensions of complexity in nature, and that higher levels of complexity exist BOTH WITHIN AND ABOVE the lower levels. This should cause you to scratch your head. How can something exist within and above something else? Let me give you an example that might start you wrapping your head around these issues. Consider the sentence, “Thiss sentence has threee errors.” What is going on here? The sentence is interesting because there are two errors at the word level and that results in an error at the level of meaning, which in turn gives the sentence its meaning. The meaning level exists both within and above the word level; it is made up of the words, but it also exists “above” them as a whole. 

Are there different dimensions of complexity in nature that are akin to the distinction between words and the meaning of the sentence? I argue yes, there are four such dimensions; 1) the physical (material); 2) the biological (living/organic); 3) the psychological (mental-neuronal), and 4) the social (linguistic-cultural). First, we should note that the higher dimensions exist within the lower dimensions in the sense that everything that is biological is also physical, everything that is psychological is also biological, and everything that is social is also psychological. Put differently, the higher levels are subsets of the lower levels. We can visually depict this conception as follows.


If we go back to Dr. Kandel’s assertion, saying that mental disorders are biological is thus true in one sense. But it also is the case that everything that is mental is also biological, including mental health. If we follow this logic to its natural conclusion, then, people are not responsible for anything because everything they think, do and feel is “biological”. We can even go further and say that because everything that is biological is also physical, we are “just” physical, just complicated arrangements of matter and energy, and are obviously not responsible for anything that we do. I don’t think that this is what Dr. Kandel was driving at.

Indeed, this kind of “greedy” reductionism does not work at a philosophical level. Why not? Because the cause-effect relationship of Newtonian mechanics does not really account for nor describe the cause-effect relations that emerge via information processing. And, since the emergence of the material universe 13.7 billions of years ago, there have been three great emergences of information processing. First, Life (or biological complexity) emerged as a function of genetic information processing. Second, Mind (or psychological complexity) emerged as a function of neuronal information processing. Finally, Culture (or human social complexity) emerged as a function of language (symbolic syntactical) information processing. Because of the nature of information processing, higher dimensions of complexity exist “above” the lower. That is, although they are dependent on lower dimensions, they are not reducible to lower dimensions of complexity. The following representation captures this.


Lower dimensions of complexity create “conditions of possibility” for the transfer and processing of information on the higher dimensions. To see this, let’s consider talking on a cell phone. When you are speaking on a cell phone, the conversation is the socio-linguistic information that is being shared. You have an idea in your head. When you speak, you are transferring that information first into muscle movements which flow through the air, into the cell phone receiver, into electronic information that is then beamed as electromagnetic waves into a receiver, into a satellite, back to your friend’s cell, through the speaker into their head and they reply. The physical mediums are necessary for such a cell phone transmission to get through, but the physics of electromagnetism does not describe or explain the content of the call you are making. But if those mediums break down, the information will be broken down and the call will be lost.

Now we are in a place to return to Dr. Kandel’s comment about mental disorders being biological and, as such, the person not being responsible. What I believe he means here is that the root cause of the problem is in biological malfunctions that result in psychosocial suffering and dysfunction. And he is saying that when there are serious disruptions in the mental/social functioning of an individual that emerge as a function of breakdowns or malfunctions in lower levels (i.e., the neurophysiology of the brain), then we can say the individual has a brain disease and is not responsible for it.

At a conceptual level, when Dr. Kandel talks about depression this is what he means. I question this approach. I claim that depression should first and foremost be defined as a state of psychological shutdown, characterized by a notable shift toward the negative and a relative absence of positive mood. That is what depression is. With this definition we can proceed to thinking about the proper recognition of the bio-physical, psychological, and social dimensions of complexity allow us to identify the way in which depression might be a disease. When that observed psychological shutdown (i.e., negative mood, etc) is a consequence of malfunction at the bio-physical level, then we can call that symptom set a depressive disease. I believe what many researchers call “melancholia” corresponds to what likely is best thought of as a depressive disease.

However, as anyone who has been down for a period of time can see, there are many depressions that are relatively easy to understand from a human psychological and social point of view. Being “depressed” is natural and not indicative of biological malfunction for people who live in extremely stressful situations for long periods of time (abuse, poverty, illness, marginalization), people who have encountered major irrecoverable losses, people who have extreme difficulty forming and maintaining intimate relationships—the list goes on and on.

Although there is a biological dimension to depressive symptoms in such cases, that is only because there is a biological dimension to everything that is psychological and social. The point is that it is a conceptual error to try to reduce such symptom profiles to biological malfunctions.

Depressive symptoms that are “understandable” from psychosocial perspectives can further be divided into two groups. Depressive reactions are when the shutdown seems adaptive. Usually, this would be in the sub-threshold or mild clinical level and in response to a clearly identifiable stressor or unmet need, such that the depression is signaling a recalibration or need to do something different.

The other category is what I call “depressive disorders”. These are usually in the mild to moderate range of clinical depression and correspond to what some call psychoneurotic depressive illness. What you have here are people who have trouble in life for a host of reasons and then become increasingly negative, withdrawn, irritable, and lacking in motivation, and this response, ironically, creates more stress, less social connection, more problems, etc., thus creating a vicious psychosocial cycle. These patterns are what the psychotherapies are designed to treat.

The bottom line is that even renowned scientists still often don’t have clear maps that enable them to differentiate between the different levels of complexity and this leads to much confusion, and ill-posed questions such as whether depression is biological or is a disease. The appropriate map allows one to define depression as a state of psychological shutdown, which can either be a normal reaction to chronic problems, a maladaptive state perpetuated by a vicious psychosocial cycle, or a pervasive, nonresponsive problem in mood that likely stems from an underlying biological malfunction (AKA, a depressive disease). 

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