I am now pretty much convinced that average and peak general intelligence (g) has been declining in the West for at least the past 200 years - and the rate of decline is at least half a standard deviation (circa 8 IQ points) per fifty years.
I have recently become aware of further evidence that the above is pretty much correct - but this is not yet published.
What this means is that we are living in an over-promoted society.
We have inherited social structures from earlier generations, with social roles dependent upon certain minimal cognitive capacities - but we lack sufficient people with the requisite cognitive capacity to fill these social functions, therefore although people can do their jobs and functions, they do not and cannot understand these functions.
Therefore when anything goes wrong or when any change is required, people will necessarily wreck what they have inherited.
It has been like giving a bunch of ten year old kids modern guns, tanks and aircraft - they can certainly shoot guns, many could drive tanks, and a few could fly aircraft - but they cannot maintain or repair the stuff - and certainly they cannot replace it.
They simply cannot do this - whether they wanted to or not (and mostly they can't be bothered, and would rather do other things anyway).
Modern people are the same with their cultural inheritance. Not just technology but religion, science, the education system, politics, administration and management, literature, music, fine arts... you name it, we have wrecked it.
We wreck it because the majority of people who do these things cannot understand them; therefore necessarily cannot maintain, repair or replace them.
Compared with (say) 100 years ago - our premier intellectuals are like their school teachers, our school teachers are like their foremen, our skilled workers like their semi-skilled, our semi-skilled workers are like their peasants, and our unskilled workers are unable (and unwilling) to do anything useful at all.
(I mean they cannot do anything useful in the modern society which we have inherited - in other societies they might perform valuable work.)
And this continues.
There is no reasoning with these people - they cannot follow reason - they are over-promoted, they just cannot understand.
What is to be done?
Start again, simplify, build-up from the ground.
But that will happen anyway, willy nilly...
Note on the phrase 'willy nilly'. From Christopher Tolkien's glossary to Chaucer's Nun's Priest's Tale: Medieval English possessed special negative forms of some common verbs; see nys, nas, nere, noot [ nys from ne is, is not; nas from ne was, was not; nere from ne were, were it not; noot from ne woot, I do not know]... The phrase 'willy nilly' still contains one: 'will I, nill I' or whether I wish it or wish it not.