As I have said before, the key ideology of the Era of Modernity, 1870s to the 1960s, was popular or vulgar Uniformitarianism, lying never far beneath western liberal capitalism democracy and fascism/nazism and socialism/communism.
In its popularly understood form, uniformitarianism claimed tomorrow would be like yesterday and yesterday was like today : and you know what today is like here in the earthquake/famine free western world.
Life and Nature today, here, is calm, peaceful, predictable and basically open to anything humanity might throw at it.
Controllable by humanity to such an extent that one could pick future winners (ideas, nations, technologies) with quiet confidence because in the unlikely evident one winner proved a dud, humanity could quickly make a mid-course adjustment.
Nature won't bite, indeed couldn't bite.
Reductionism of gene and idea pools (and hence of possible alternative visions) quickly followed : pick the scientifically determined winners and bin the rest, with Zyklon B if need be.
The Science of Certainty : freely reduce the gene pool
The very massive and yet very secretive Manhattan atomic Project was the apogee of such thinking.
It was 'Big Science' in terms of the number employed by it, but 'little tent' in the number of those employees, let alone the general public, who were informed of its ultimate purpose.
Speaking of Zyklon B, after the revelations of Auschwitz and the perfecting of global death via V2 rockets and atomic bombs, human catastrophe caused by the most sophisticated civilizations seemed to not just be possible, but inevitable.
Then, in 1954, there was news that airborne radioactive fallout from one thermonuclear bomb (Castle Bravo) in the remotest part of the South Pacific could bring death to human and animal babies all over the entire world.
This raised the stakes even further.
For now human-originated catastrophism could affect the entire biosphere, which clearly was interconnected as all Life was shown to dine at a common table, now covered in radioactive dust.
Enter stage left : Catastrophism
Lyell's ancient intellectual rival, popular Catastrophism, (the idea that some catastrophe can affect the whole world and humanity can't stop or control it) was suddenly back in discussion, at least in terms of catastrophes of a human-originated form.
But if one globe-wide catastrophe existed that humanity couldn't stop or control (in the form of all-out thermonuclear war/nuclear winter/global fallout's triple combo) then why not others of human, natural or even cosmic in origin ?
Some young scientists suddenly dared to look at the effects of past Ice Ages, beyond just their obviously mobile massive ice caps.
For the evidence of a North American continent wide massive flood of truly biblical proportions, caused by by a break in an ice dam and possibly affecting global temperatures even in areas beyond that covered by ice caps, had been known for a half century but had been strongly denied by the scientific community.
Scientists, en masse, back in the era of Modernity all saw the financial virtues of backing uniformitarianism.
It was essential to maintain a united front about uniformitarianism if they were to advance the then new claim that scientists should be paid big salaries, given lots of grants and treated with god-like status.
All on the basis that uniformitarianism proved that the future was predictable and was controllable and that they were just the boys to do it.
Admitting that there were global-wide disastrous catastrophes that scientists couldn't see coming or stop once recognized (popular catastrophism) was simply not good for their careers and pensions.
But the younger, postwar, scientists were much influenced by the fact that paying scientists good salaries and granting them high status and public money for research was now an established fact, so at long last they could be more honest about studying things they couldn't actually prevent or control.
There is my army, I must run hard to lead it...
In fact, they recognized that today's scientists had to be more upfront than their scientific elders had been about the possibility of scientist-caused global catastrophes like nuclear war --- or risk losing all that hard earned status with the public.
Because the least sophisticated of the general public was well ahead of them on this score : the sudden rise in popularity of global disaster-oriented science fiction films in the early 1950s was proof of that.
Some still think the films' radiation mutated giant bugs were really Russian communists in disguise : I think they were simply seen as giant city eating bugs and the result of mutations caused by nuclear tests.
Human global pollution effects (such as acid rain), human climate change, overfishing and species loss, on and on were soon added to the score.
Global pandemics like 1918's Spanish Flu were now re-cast as global catastrophes, capable of - on the actual record - of reaching into even the remotest of isolated islands to kill and maim.
And man's overuse of antibiotics was spurring on bacterial resistance that, coupled with global air travel, could see old and new pandemics arriving at the speed of sound and yet be unstoppable by the best in medical science.
Even the continents no longer bobbed up and down placidly in place but trashed around and smashed into each other as tectonic plates - yet another old set of evidence denied at the time as a threat to uniformitarianism but now accepted as scientists struggled to stay intellectually ahead of the young drive-in movie set.
And why stop at natural and human sources of global catastrophes ?
What if a giant rock from space - the sort that scientists were finally (at long last !) admitting they couldn't see coming with present technology, let alone stop, caused all the various mass extinctions of species.
Soon it appeared that indeed one such rock did kill off all the dinosaurs and much else besides.
Diversification of our gene and idea pools : the Science of Uncertainty
If Modernity and Big Science was about plumping all your money on just one high yielding blue stock, on a company selling something you sure would be popular long into the future (say newspapers for example - at their peak in the early 1950s), the post-modern, born after 1940, drive-in set wanted to hedge their bets.
Better to spread your investment widely, better to diversify your portfolio - maybe homos, cripples, women, negroes and darkies in general might have usefully talents and ideas as we faced a series of upcoming global catastrophe.
Better then lots of different little (DIY even) sciences and seeking a Big Tent of all possible talents.....