Today, the largest purveyors of "neo-Malthusian" ideas are greens. Within the greens there's little opposition to it because most of the green organizations are anti-growth. At its simplest: anti-growth = neo-Malthusian. It goes further than that. Many of the original greens believed environment protection required zero- or negative- economic growth because they see the world as a zero sum economy: a resource spent on A is automatically something that can't be spent on B. The greens of 45 years ago were quite explicit:
"it’d be little short of disastrous for us to discover a source of clean, cheap, abundant energy because of what we would do with it."- Amory Lovins (1977)
"Giving society cheap, abundant energy would be the equivalent of giving an idiot child a machine gun."- Dr. Paul Ehrlich (1970)
These greens were politically and intellectually neo-Malthusian. Their politics needed it and neither their ideas, nor policies could escape it.
we also thought that as you provide societies with more energy it enables them to do more environmental destruction. The idea of tying us to the natural forces of the wind and the sun was very appealing in that it would limit and constrain human development.- Robert Stone (2014)
They were particularly scathing on energy because energy is the master resource behind industrial society. Using energy to replace labour allowed Britain to become the dominant world power in mid-Victorian times. It's no accident that the end of slavery coincided with the mass use of fossil fuel. Today, it's behind the economic growth of North America and its relative lack is a factor in Europe's slump. China - the workshop of today's world - has the cheapest electricity anywhere (at about 8¢/kWh). Nuclear energy was at the apex of their vitriol because it is by far the densest form (over a million times denser than fossil fuel). The leaders of the early green movement were generally well educated at a time when higher education was far more rationed than today. They weren't neo-Malthusian out of ignorance but out of choice. Todays greens still have this mindset. Even when their instincts are in conflict with zero-sum they don't have the courage to contradict green orthodoxy. So, they are either intellectual cowards or neo-Malthusians.
Naturally, all economic thinking trucks with zero-sum thinking. The peculiar aspect of neo-Malthusian ideas is that zero-sum thinking crowds out everything else. This is dangerous because our natural tendency is to see a zero-sum economy: just listen to Parliamentary debates, (or read CiF debates). We must always be on the guard against zero-sum. Zero-sum economic thinking strangles any possibility of socially progressive thought. A zero-sum economy will make progressive society impossible. In a neo-Malthusian world where everyone's fighting over smaller slices from an ever dwindling pie, there can only be reactionary economic systems and politics. Modern novelists celebrate this with ever more dystopian visions. Progressives should fear it.