On what grounds do people choose their ultimate (metaphysical) assumptions about Reality?

I am slowly and carefully re-reading Owen Barfield's Worlds Apart (1963) - one of his best books - which is a profound 'Platonic dialogue' between characters representing different philosophical and scientific viewpoints. 

I have just worked through sections in which Linguistic Philosophy, and then Freudian Psychoanalysis, are expounded: firstly in all their irrefutable nature, as if each 'must be' true; and then revealed to be wholly a product of assumptions that have been chosen.  

This is how it is - at least in our era: we choose our reality by choosing our fundamental assumptions about the nature of reality (i.e. metaphysics; which is that philosophy which is concerned with the deepest assumptions of the nature of reality). 

Choosing and accepting different sets of assumptions leads to different world views - each of which is irrefutable once entered. If you have ever talked with a Marxist, Freudian, or SJW - you will know that there is no possible evidence that does or could refute their system - once the assumptions of that system are accepted; and, indeed, exactly the same applies to a Christian of any denomination, or to adherents to other religions. 

The conclusion is that our relationship with the world is rooted in metaphysical assumptions, and these assumptions are chosen... Thus we choose our reality. 

So what determines our choice of assumptions? Why does somebody choose one reality rather than another? In particular - why do so many people choose assumptions about reality that lead to a miserable, futile, meaningless, demotivated life? 

To be specific, and to take a mostly-past example, why did so many people (especially Americans) choose to believe Freudian Psychoanalysis was the truth about reality; when that reality was so utterly nihilistic? 

Those who chose the metaphysics of psychoanalysis could, in principle, have chosen assumptions that sustained purpose in life, life beyond death, and a meaning in life that included real and eternal relations with other Men, Nature and God... Yet all this was rejected in favour of embracing psychoanalysis...

As an up-to-date example we have the dominating, hegemonic, political attitude of 'leftism' (including All mainstream political groupings and parties) - which again is rooted in metaphysical assumptions that see human life as purposeless, meaningless, and oppositional (rather than creative) in its ultimate nature. 

Why would anybody - so many hundreds of millions of people - choose to believe assumptions that lead to such a pointless and worthless concept of their own (and everybody else's) life?

I think we can see the answer in terms of a basically perverse attitude, that regards anything bleak and depressing as thereby true. 

There is a prior, and unconscious/ unarticulated, assumption that anything true, beautiful and virtuous is a fake. 

This is the idea that has, for the past century, sustained high-status art and literature which is overwhelmingly (and deliberately) hope-less and hope-destroying, disgusting... Which assumes that life is futile and seeks to reveal the selfishness, hedonism, manipulation that lies beneath all apparent 'good'. 

In other words; people in The West overwhelmingly choose to choose a reality in which evil is true, and Good (and God) are fakes. And they regard anything else as childish, ignorant, deluded - or some kind of fraud. 

Where does this attitude come from? I believe that it is rooted in the pre-mortal nature of those people who are incarnated in the modern era; amplified by evil-choices un-repented, and reinforced by the society which these people have built. 

In other words, the ultimate cause is the innate nature of Men; but Men are free agents; and their disposition does not dictate their choices. Yet men have, overwhelmingly, chosen to make choices to disbelieve in God, the soul, the spiritual world; and more recently to reject God and favour the side of the devil. 

Men are not naturally Christian, but have chosen actively to reject Christianity, including the promise of eternal resurrected life - and to regard it as an evil which should be eradicated. 

Thus Men who were born with a greater disposition to evil, and a lesser spontaneous knowledge and experience of the divine, have amplified (rather than repented and worked against) these traits; which is why Men (in the West, primarily) have overwhelmingly and increasingly chosen to believe nihilistic metaphysical assumptions. 

My conclusion is that people actually choose the reality they live-by (whether consciously, or mostly unconsciously); and most people in The West have apparently made the choice to believe ultimate assumptions about reality that lead to the conviction that life is futile and without coherence, and is extinguished at death.

This, in turn, leads to a conviction that there is nothing to be learned from life, that the short-term is the only dependable reality, and that our personal state of happiness/ pleasure (or misery/ pain) is the only reality that really matters. 

There is no long-term (especially not eternal) purpose; so there is no long-term or strong motivation. 

There is no reason to remember experience (because our reality is not permanent in value), and no possibility of valuable learning (because here-and-now is the only dependable truth) - therefore people try (as best they may) to live in the present, and to live in accordance with... whatever incentives are most dominant in the present.  

So far it seems that our dispositions tend to dictate our choice of assumptions; but of course we are (by our nature) free agents and able to choose differently. 

But we can choose differently only if we are consciously aware of the fact of our choosing. 

If we are unaware that there are metaphysical assumptions, and that we have in fact chosen to believe some assumptions rather than others - then we are trapped; because the assumptions dictate what counts as evidence. 

Freudianism (or Marxism, or Scientism, of Christianity...) explains all possible 'evidence'; therefore only when the Freudian realizes that he has chosen to believe this and this as his assumptions concerning the nature of reality, is he then able to choose differently. 

What might be his motivations for choosing differently? 

Well, at one superficial level he might want to choose the beliefs that sustain the 'happiest' possible life, in which there was present those motivations that are subjectively most satisfying. But in practice, that does not seem to work - modern men are pre-immunized against this; by the assumptions that such happiness-seeking people are mindless, gullible fools; or else cunning manipulators.  

We cannot, of course, make an appeal to 'the truth' because that is begging the question: The Truth is precisely what needs to be established by choice of assumptions. Once someone has already made a choice of assumptions (and this applies to all post-adolescents), then 'the truth' of whatever he has chosen is confirmed by all subsequent experience. 

I think the only possible motivator to change assumptions is intuition, that deepest and most ineradicable of evaluative inner convictions. 

If the Freudian can get to the point of recognizing and becoming aware of his own primary assumptions and the fact that he has chosen to believe them rather than other assumptions; then intuition can (and will) get to work on them.

All assumptions are chosen in modernity - yet intuition recognizes some as arbitrary while others 'ring true'; some assumptions are dead, inactive, unsustaining - while others awaken motivation, creativity - and Love. 

Perhaps Love is The most important thing. Anyone who is capable of Love and values Love; will find his intuition working on his own core assumptions, evaluating them in terms of Love. 

And it is Love that leads a Man to reject the assumptions of Psychoanalysis, Linguistic Analysis, Scientism, Leftism etc... (i.e. recognizing them as love-denying, love-less and love-destroying assumptions) and which begins to move his choices towards Christianity...

And - by Love - within Christianity; his chosen assumptions will move towards that true Christianity that was exemplified and taught by Jesus Christ - rather than the errors and perversions of Men.