It is a fact that for many people the world seems 'dead' - this is the sense of alienation.
The fact that people do not find this strange, and seek to defend the idea - and indeed to propagate it actively by all possible means - is what invites explanation. There seems to be a very strong desire among some people that they themselves must regard the world as dead, and that they want to ensure that everybody else also regards the world as dead.
If asked, probably they would say they want this because it is just true; but the same people show no apparent interest in other and much solider truths - so such an answer is irrelevant.
There is a real edge to the propagation of the idea that the world is dead - those who propagate the idea (and who scorn, mock or vilify those who perceive and feel the world as alive) seem to be driven by something strong, insistent, demanding.
I think there is real fear behind the insistence that the world is dead - visceral fear. Fear of what? Fear that the world is not dead, presumably; and therefore what we do to the world is being done to a living entity.
But why should this evoke fear? Is it merely a primitive and superstitious and unrealistic fear - or is the fear based on something else? And, anyway - assuming they really exists - where did those primitive (or as moderns say 'medieval') superstitions come from?
The visceral nature of these emotions suggests some kind of personal involvement in the issue, and I suspect this derives from our memories (often implicit) of being children for whom the world was indeed alive. At some point almost everybody drops this belief, and changes to deny that the world is alive.
In some sense this change must come from a combination of maturity and experience, but the role of maturity seems to be to sensitise us to some experience (because the change to reject the aliveness of the world does not happen in all individuals societies, or is a temporary phase).
So if alienation and a permanent and ineradicable sense of being cut-off from life is the natural consequence of regarding the world as dead - then what is the compensatory advantage? Probably, the sense that the world is there to be used for our personal benefit - to make us feel better here and now and whenever we want.
Modern science is the apotheosis of this view - in that the world of science is set-apart-from religion, theology and philosophy (on the basis of certain, then-forgotten, metaphysical assumptions: this is the founding of 'science' as a distinct discipline) - and indeed as science evolves, one science is set apart from another; not just temporarily for the expedient attainment of certain types of understanding, but permanently and as a matter of principle.
The world is cut up into by-definition-dead chunks and examined - then used - on that basis. And the rationale for doing this is accepted as intrinsic assumption-free reality.
The invisibility of assumptions - first the creation of science by working within a set of metaphysical assumptions, then the denial of the reality or relevance of metaphysics, the denial that there any assumptions are being made... that thing again!
Maybe it is the root of what is going on with the dead world. At some point in our life we assumed the world was dead and explained everything on-that-basis. Then, after a while, we found ourselves regarding our picture of 'the world as seen through dead-world-spectacles' as evidence that the world really-is dead!
We made an assumption, lived by that assumption - and then the assumption became its own evidence, hence invisible!
If it is all a matter of assumptions - and it is - then why the vehemence!
Perhaps we sense that Modern Man is addicted to his dead world, because of the short term and selfish benefits this perspective brings (comfort, convenience, distractions etc - taken as of right). We perhaps sense that all this will have to stop if or when we regard the world as alive... that the whole edifice of 'entertainment', fashion, time-filling - of life as something we use or consume - all this will have to go.
And, because we are addicts, the thought is intolerable...