Low population density - which usually goes hand-in-hand with lack of diversity - is not the same as solitude.
In my opinion those enduring actual solitude are less likely to exhibit the kind of mass stupidity Bonhoeffer was talking about, but they are still liable to develop their own idiosyncratic forms of madness or eccentricity. It just doesn't have much social effect because it isn't a mass phenomenon.
I guess I don't disagree with the OP argument.
I think this is the important point. One very widespread technique used in teachings oriented around the pursuit of enlightenment involve withdrawal from society, hermitage and meditation, monasticism, etc.
"Stupidity" has always seemed to me to involve a very large element of deliberate choice. It's usually about incentives. People fail to reason correctly because they have a vested interest in doing so.
It's reflected in that (Upton Sinclair) quote about “It's difficult to get a man to understand something when his salary depends on not understanding it." Or in the research that shows people's mathematical ability deteriorates if the math they are engaged in relates to a topic they feel politically invested in.
The question I would ask you here is whether you can actually use the word deliberate to describe the kind of incentivized vested interests choices we make. A conscious choice to act out delusional behavior would imply that a person so engaged would not be engaged in any self deception which I think is obviously wrong. The whole thing is based on self deception, in my opinion, without any awareness that is actually what is happening. That leaves me to ask you what then, other than the vague terms incentives and vested interest, those phenomena actually are. I believe the incentive is preservation of ego status where the vested interest is to preserve ego identification with something out there in the world to hang onto as a substitute for the self worth we once had naturally and innately as children before being made to feel worthless by being put down. As a thinking person this should be obvious to you especially when explained, were it not that you also have a vested interest in not seeing it.
On the other hand, it's probably impossible to live in an entirely 'rational' manner, like a Vulcan. Life would probably be unendurable without delusions.
Indeed, that is exactly the feeling you fear to be true. In my opinion you are completely wrong here. It may, also, and again in my opinion, account for the depression you have suggested you suffer. It isn't so much a matter, IMO, of being rational as it is of being free of the need to believe anything that is the product of thinking. In short it isn't the realization of answers but the cessation of a need for them. There is a switch that can be magically flipped from no to yes, from struggle to surrender, from thought to presence. Then one may suffer in reality, but not existentially. Two different things.
Saying "Personal anecdotes are irrelevant" seems like a great way to excuse treatments not working. Makes them unfalsifiable.
And I've seen a few studies reported that found SSRIs (and talk therapy also) to be no more effective than placebo.
Also, if this 'placebo effect' is so good, how come it never kicked in for all the treatments that I _did_ believe in? I only came to doubt SSRIs after having umpteen different ones for extended periods with no effect. How come the placebo effect only kicks in when it's useful to explain away a treatment not working?
Excellent questions, I think. In my opinion, and as I tried to suggest to
@woolfe9998 earlier, I think the pharmacological treatment of some forms of mental issues may have a scientific validity. But like the rest of the world, I do not think that psychotherapists, generally speaking are aware they have the same disease they are trying to treat. I think also that the scientific study of the human population is the study of people who are sick, and the the aim of psychiatry isn't to heal but to help people cope with their illnesses. The cure is enlightenment not adjustment to being insane.
I believe I had a real therapist once long ago, from whom I learned a lot before he died, for me a staggering loss. His methodology was group and individual psychotherapy with one single aim, to feel what we really feel. If all you did was only talk in individual therapy he would fall asleep.
I don't know anybody practicing like that today. Hopefully somewhere someone is.
PS: I forgot that I wanted to ask you about your depression that drugs don't seem to help. I am going to assume that being depressed is not something that is pleasant, that you probably wish you didn't have it. If so, the question that drove me is , Why do I suffer? Why do I suffer. Why why why! Why do you suffer? Not asking you to tell me only, "Is that a question you have?