The only addition I would like to make is a subtle and seemingly minor one, but it does make all the difference in the world.
The basic premise is that for a social system to change, values must change first. In your picture there are policies and social response to them. True, the society does respond to policies in both psychological and economic terms. But where have policies come from? How come there was a majority consensus to implement them?
If you look closely, it is always a small group of culprits that promulgate the change, whether it be communists in Russia, Nazis in Germany, or the anti-American part of the education elite in this country. But in all these cases, these minorities are successful only in a moral vacuum. So, whenever you see a change that you do not like, look for that vacuum first --- that is the hard part, the actors of change is usually hard to spot.
It is the slow but constant retreat of religion in the Western World, starting from the XIX century that is the real cause. This retreat has created a vacuum, into which socialists stepped in. It is my theory that the Church was slow to respond to the industrial revolution that created mass migrations of people and drastically changed the inter-personal relationships between people, from families to social classes. Ever since then the religion --- not only Christianity but Judaism as well (although the former is clearly more important in social terms for obvious reasons) --- have been on the defensive. That is, the religion, the source of our values, is in a reactive mode. The latest is the contraceptives "revolution," to which the religion still struggles to find a proper response.
In contrast, the social engineers --- communists, socialists, feminists, you name it --- have the initiative and dictate the terms. The masses are sufficiently confused by the social inventions of elites precisely because there is no adequate response within a traditional framework. This is the climate that makes possible the introduction of policies that you identified.
Like most people, you have presented what I call the first-order theory: it deals with the question, "What should the policies be." Everyone and his dog have an opinion about that. But the real question is, "Which society, with which values, will adopt these `optimal' policies." In simple terms, it is not enough to formulate the proper policies --- someone has to be convinced to vote for them. Thus, the social values are very important. The root lies therefore not in the sphere of politics but elsewhere. It is more likely to be found in the church and at the family dinner table than at the presidential debates.
Regards, TQ.
My initial thought is the following.
The potential for radical and destructive movements to gain control of a society is always present. The French revolution, Peronism, and Communist Cuba are three examples that come to mind.
The Founding Fathers knew their history in regards to destructive movements and tendencies within societies. They built safeguards into the Constitution in recognition of this fact. Safeguards such as the Second Amendment and Tenth Amendment are two examples.
So, I don't know the common denominator as to why traditional values sometimes lose their hold on a society and permits such things as socialism, communism, etc. to take hold.
The fact remains, it does happen and it happens frequently.
Finding the root cause is worthwhile but ensuring that the safeguards in the Constitution are defended takes higher priority, IMO.
I will give some thought to the question of why traditional cultural values weaken in people in the first place, because it is an interesting one. I expect if you posted it as its own thread, you'd have as many different answers as posts. I'll try to come up with my own.
Regards