Asking what might be different had different ideas arisen, begs the question of whether different ideas could have arisen.
Assuming the universe isn’t like clockwork, with everything determined from the Big Bang, it seems clear that chance events in history (like Stauffenberg’s bomb intended to kill Hitler failing because it was nudged slightly behind a table leg by someone’s foot), could have played out differently. But is all that dearly held knowledge in libraries also dependant on historical accident – today’s heavy textbooks on genetics entirely dependant on the decision of a nineteenth century Augustinian monk to spend his time counting peas?
The ‘heroic view’ of scientific discovery with which we are all familiar, that of a lone genius, Newton under his apple tree say, having a sudden flash of incredible insight and conjuring up a world changing theory, would seem to be quite susceptible to historical accident. What would be holding up our satellites had that apple not fallen on his head?
I think this view of scientific discovery is pretty much dismissed now, and reassuringly so, because the idea of physics ‘stopping’ if Einstein had slipped over in the shower or something is sort of alarming.
The lone genius also doesn’t make sense given that history is littered with cases of multiple people, independently making the same discovery or invention at the same time: The telephone, patented on the same day by Alexander Graham Bell and Elisha Gray, the lightbulb ‘invented’ independently sixteen times, electromagnetic induction discovered both by Michael Faraday and Joseph Henry in 1831, the theory of evolution credited to both Charles Darwin and Alfred Russell Wallace… There are far too many instances of multiple discovery to list here (try here instead), in fact Merton’s theory of multiples holds that simultaneous discovery is the rule rather than the exception.
So (in contrast with chance events), ideas could ‘happen’ inevitably – when the conditions are right an idea is ‘in the air’, there for someone (or more likely ‘many-ones’), to pluck it and give it expression.
This is quite a deterministic view of knowledge, which suggests the ‘modern world’ couldn’t really be any different from the one we live in today.
Does this mean Science must be true?