> That would still have to be weighed with [...]
As always you'd have to determine whether some course of action would have disproportionate negative impact on other objectives, yep. Point there was to set out on what basis I'd decide and weigh those objectives - an orientation for what "progress" is.
> And what destructive or dangerous uses are now unlocked along that path?
I believe unanticipated novel applications skew positive on average, largely on account of most humans having mostly-positive intentions.
> What's the scope for those stats, are they global of specific to one country?
Global, e.g:
* https://ourworldindata.org/grapher/life-expectancy
* https://ourworldindata.org/grapher/share-of-population-livin...
> but I've seen plenty of examples of the extra years being pretty miserable. I'd be very interested to see a life expectancy comparison taking into account quality if life.
You could consider a factor such as Quality-Adjusted Life Expectancy (QALE), which is also on the rise.
> The point with defaulting to the latter is "don't break a god thing."
If "break" means "make overall better", why not?
> Considering only the potential upsides misses the potential downsides.
To be clear, my stance is that you should consider whether it's a net positive/negative:
* "Threshold for new advancements should not be whether we absolutely need it, but whether it does more good than harm"
* "if we're at 500 malaria cases and can reduce it further (without equal/greater degradations in other areas) then I don't see why we should ever be "happy to stop there""
My understanding is that you believe there should be some point at which we just stop even if there are still more beneficial changes to be made (in addition to not making net-negative changes, which we both agree on - though perhaps disagree about what specifically works out to be net-negative).
> We can't cure cancer in a vacuum, there are always costs,
There are costs, but it's very easily possible for the benefits to outweigh them, and more becomes feasible as humanity's knowledge/capabilities increase.
> and frankly the idea of curing a disease seems more utopian than realistic.
There are already a couple of diseases (including smallpox) that we've completely eradicated, and more (like polio) that we've made very good progress on. Cancer is tougher by its nature, but we can certainly at least reduce the number of cases and improve life for those who have it.