To be sane is to be in touch with reality, to be in touch with reality means (minimally) having a coherent perspective.
To have more than one perspective - to be thinking one way, then another, then another; and to lack a basis for ever combining, sequencing, stratifying these perspectives - is to be insane.
It is to lack any basis for deciding-between persepctives - merely to be trapped by whatever perpective is currently in-place.
There is no basis for deciding the importance of events, neither their absolute nor relative importance - on a scale between overwhelming of everything/ nothing else matters or utterly trivial/ ignored, the same event might be regarded as either - and there would be no coherent argument about which.
Between events, between possible subjects of attention - there is no basis for allocating attention, or resources, or concern.
There can be no long term purpose, no coherent planning - because there is no relative scale of values; no value as higher than another; all are 'ends' and none are means-to-ends; life is merely one thing, then another, then another.
Each specific perspective is partial, hence false; it leaves-out most things (to make it simple) and it is biased (no specific perspective is a microcosm of reality - rather it is a tiny chunk of reality of unknown relationship to the whole - that could only be known if the whole were known: if there was an underlying coherent perspective).
Modern societies are differentiated into perspectives - these are the specialist social institutions - politics, law, military, religion (in the past), the mass media and so on. Each makes its own selection from reality and works by its own rules... There is no underlying master perspective - no meta-narrative.
In other words, in modernity there are many selves and no ultimate real self. Each perspective can be conceptualised as a separate self, processing the world differently.
This happens in modern people, as well as modern institutions. We have many selves. Some we have learned in order to perform certain functions - one self does our work, and within that are several separate selves with various skills, When such a self is engaged, the world is seen and understood from that self.
But whenever another self is engaged - then another and different self becomes the locus of our subjective-self - when watching The News, on Social Media, engaged in sports, with family, engaged with one or another of the many bureaucracies that constitute our world (each with somewhat different rules).
Our subjective self moves between these many selves - some natural, some self-training, some inculcated by socialisation, others by propaganda.
Most are taught that there is no real self - just a sequence of specific selves - to be adopted temporarily then cast aside as another is picked-up. This is the ordinary, unremarkable, universal experience of being-adapted-to modernity. And it is insane.
We are insane, because we move between distinct false selves; and the society is insane because it does the same.
Insofar as there is convergence of social systems to one socio-political system (of secular Leftism) or there is convergence of our personal systems to the one system of political correctness; these are merely establish insanity more solidly; since the ideology on which there is convergence is negative and oppositional. It is an ideology without purpose or aim - except destruction of The Good.
Convergence on evil is not convergence on sanity; it is the active embrace of insanity: a species of value inversion.
So we are, each of us, insane; and we live in an insane society - the the depth of our insanity is measured in terms of tour will assent to and embrace of this insanity. It is not merely that we have not (yet) found coherence and sanity - but that we believe there is no coherence to be found; and indeed we have a morality which would reject such coherence if it did exist.
In a world of actively embraced and aggressively promoted insanity; the one priority above all others must be restoration of sanity: first in ourselves, then in others.