Eric Holdren said I was insane to believe that 9 billion people could have personal VTOL ballistic vehicles at their homes, consume at the same level multi-millionaires do today, and maintain a clean safe and sound environment and biosphere.

What you think is sane and not sane says a lot about you as a person, your vision and so forth.

Of course, he was not making a medical pronouncement. He was saying that a world of 9 billion people sharing a highly industrial life style was silliness and that the technical means to do that was irrational while any attempt to do that was foolhardy given the serious nature of the difficulties we faced.

For me, his views were equally foolhardy. While he ranted against what he called growthsmanship in many of his writings, I see it as the only way forward.

While extreme views at either end of the spectrum are examples that can be used to marginalize either view, its clear that humanity is characterized by its ability to modify its environment to improve its reproductive success..

As we grow from Type 0 to Type 1 civilization, we will need to take care of the biosphere, rather than have the biosphere take care of us. This is a fundamental shift of consciousness Holdren resists, and I embrace.