This is an interesting question which you pose very clearly. Because we don’t know the future and what opportunities technology may bring, it is prudent to hedge the risk with an insurance policy. Right now we aren’t doing that and instead are doing the equivalent of driving fast without either a seat belt or insurance cover.

I’m not quite sure how we would hedge against 70% acquifer depletion, climate change or soil degradation, but a more honest conversation about the need for a hedge would be a start.

And looping back to your question, how to tell the difference between the Malthusian and the correct...and realizing you are essentially asking how to work out who is right and who is wrong about an unknowable future...maybe we look to how honest they are about the inherent uncertainty in any predictions made about the future, and secondly about the need to take risk mitigation steps to avoid worst outcome scenarios.

I'm not sure there's a real distinction. You make predictions based on evidence, and you're either right or wrong.

Equally flawed is taking on faith that technology will save us from ourselves.

its really amazing how Malthusian ideology is so pervasive in public thought, when the data shows that it is wrong just about everywhere you look. Even India's population growth rate is going down (has been going down since the late 1970s, source: google india population growth rate chart), and they are the poster child for population growth. Japan was the first country to post a population loss, but other countries will follow shortly

Africa is the concern on the population front.

I sort of feel we need Malthusian pessimists to warm us when we are heading for the cliff. The Green Revolution, and what it achieved in India and elsewhere, was achieved in substantial part through public investment in research. I guess we’re all rather glad we didn’t continue blithely believing the Gods would save us from the Malthusians! Right now, the Malthusians are warning us of the physical limits to further crop productivity increases. I’d take this as a signal that we need to start investing in solutions!

Africa has a lot of arable land that's uncultivated. So I'm not sure the Malthusians are right this time about crop productivity increases worldwide. Google tells me there are 600 million hectares in Africa, which is 60% of the world's total. That's a lot of potential food. Also, much of exiting agriculture in Africa is inefficient, and could be increased.

Much of Africa’s soils have only 20 years of harvests left.

This paper, by the British Warren Buffet, explains the problem and is well worth the read if you have the time. It’s well-written so not as daunting as it’s length otherwise makes it look.

https://www.gmo.com/docs/default-source/research-and-comment...

Resources are finite. A certain number of people will overwhelm the availability of resources. The fact that we are currently below that number does not make the theory wrong.

There's also the technological progress of fracking, a large proportion (20-50% per county in Texas for one example) of fresh water is used once for fracking.