In 1968, 50 years ago, Paul Ehrlich and his wife published The Population Bomb, which famously predicted mass starvation by the end of the next decade. Ehrlich’s predictions failed largely because of the green revolution, the dramatic increase in agricultural productivity. You would think that being famous for a dramatically failed prediction would bring humility, but Ehrlich is still at it. In a recent interview he argues that the collapse of civilization is a “near certainty” within decades.

Let’s examine some of the logic at work here. First, just because Ehrlich was wrong before, that does not mean he is wrong now. It is certainly cause for skepticism about his current claims, because he may be laboring under the same false premises that drove his previous false predictions. We need to take a look at his claims and see if they hold water.

Ehrlich basically argues in the interview that he was mostly right 50 years ago. He may have gotten the details wrong, but his basic point that overpopulation and over consumption will eventually doom us is still valid. While this interpretation is transparently self-serving, he is not alone in this opinion. A 2015 opinion in the NYT also argued that Ehrlich was essentially right. Paul Murtaugh writes:

Ehrlich’s argument that expanding human populations cannot be sustained on an Earth with finite carrying capacity is irrefutable and, indeed, almost tautological. The only uncertainty concerns the timing and severity of the rebalancing that must inevitably occur.

Well, sure. If you reduce Ehrlich’s argument to – the Earth has finite resources, and so we cannot expand our population without limit, of course he is correct. That is a trivialism, without adding any real insight. The parts that Ehrlich did add were clearly wrong.

Why Ehrlich was so profoundly wrong in his specific predictions is instructive, and I think puts his current doom and gloom predictions into context. Ehrlich assumed a zero-sum game, and a linear advance. This is the mistake that many futurists make when trying to extrapolate the present into the future. If we simplistically extend current trends into the future, those trend lines always get scary. It will always seem as if the system is going to break, we are going to reach peak whatever, or we will run out of some resource.

History, however, shows that technology and advancement has the potential to change the game, and that future advance can be exponential, not just linear. The green revolution was the specific technological advance that rendered Ehrlich’s predictions almost instantly obsolete. We would be naive to think that no further such advances are in our future. So far we have been able to do more with less, to solve some of the unsolvable problems of the past, and to change the game when necessary.

In the interview Ehrlich also shows that he is not taking a thorough look at the evidence. He appears to be cherry picking to make his case.

“The evidence we have is that toxics reduce the intelligence of children, and members of the first heavily influenced generation are now adults.”

He treats this risk with characteristic dark humour: “The first empirical evidence we are dumbing down Homo sapiens were the Republican debates in the US 2016 presidential elections – and the resultant kakistocracy. On the other hand, toxification may solve the population problem, since sperm counts are plunging.”

It is simply not true that children are getting dumber. In fact, people are getting smarter, by about 3 IQ points per decade. This is known as the Flynn Effect. Worse, saying that the current political situation in the US is “empirical evidence” of a toxic effect on intelligence is absurd and scientifically naive. There are so many variables at work here, mostly cultural, that to link recent political events to a biological effect on intelligence reveals Ehrlich’s loose relationship with science and logic and his dedication to his narrative.

Regarding sperm counts, they are indeed dropping (by about 50%), but Erhlich makes the same mistakes again. Even assuming the drop is real (there is still some controversy, but the latest data does support a real drop) we cannot extrapolate the current trend lines indefinitely into the future with any confidence. So far the dropping rates have not significantly impacted fertility. We also do not know the cause, and you cannot confidently assume it is a toxic effect. It may well be due to increasing obesity rates in Western countries. Any plausible cause is likely to level off, and once we identify the major cause(s) we will likely be able to solve them.

On the other hand…

But I do think there is a kernel of truth to concerns about the future sustainability of human civilization. We should not fall for the opposite fallacy – assuming that problems will take care of themselves. My favorite example of this is Y2K. Doomsayers warned of dire consequences to this computer programming snafu, dire consequences that never came about. Afterward, some argued that the dire predictions were unjustified, as evidenced by the fact that everything worked out. However – the reason there were no dire consequences is because there was a massive effort to correct the Y2K bug in the decade leading up to the year 2000.

More generally – problems do not always just magically work themselves out. People see a problem looming, and they make a concerted effort to head off the problem. When they are successful, they rarely get the credit they deserve, because the problem never manifested and so people don’t notice the non-event. If the CIA and FBI prevented 9/11 from happening, they would not have received the credit they would have deserved, because the world will have hardly noticed nothing happening. If they had announced, hey, we just thwarted a potentially massive terrorist attack, the response would have been a shrug and then business as usual.

The same is true of the green revolution. Real recognition of the advances in modern agriculture and what this did for the world are not as widespread as they should be (as evidenced by all the pushback modern agricultural techniques often get). There was no mass starvation, and so most people did not notice the non-event. But that nothing happening was the result of a specific effort to solve limiting factors in food production.

In other words – the lack of a doomsday scenario should not breed complacency. We do need to anticipate potential problem in the future and make a specific effort to head them off.

I also think it is legitimate that the current and growing world population gives us less wiggle room. Everything that humans do has a massive effect on the environment, because there are so many of us. We are exceeding the pre-industrial carrying capacity of the planet, only made possible by modern technology. This makes us dependent on that technology and the systems that maintain it. So we have to think about things like, what is happening with all that plastic we are producing, are we taking fish out of the oceans faster than they can be replenished, and what is the effect of all that CO2 we are putting into the carbon cycle? These problems will not solve themselves.

In the end I have a balanced view. I do not think civilization is going to collapse. That is a Cassandra prediction that ignores recent human history, and makes naive assumptions about the arc of technology. On the other hand, we should not be complacent or ignore problems on the assumption that they will magically solve themselves, that whatever technological advance that does happen will fix things for us.

Rather, we need to think about how to have a small and sustainable footprint on our planet, how to maintain as many natural ecosystems as possible, and how to limit the negative effects of our technology. We do need to anticipate possible problems, and prioritize research and development for possible solutions. I am confident we will find those solutions, but we need to look, and knowing what to look for means thinking about possible long term effects of our current practices.

This balanced approach is similar to the role that anxiety has with individuals. If you have no anxiety about the future and potential threats or harms, you will be careless and reckless. If you are overwhelmed with anxiety, you will be paralyzed (or perhaps desperately overreact) and depressed. There is a sweet spot in the middle – enough anxiety to invest for the future, prepare for possible risks and avoid threats, but to also happily live your life. I think collectively we are there. But this is a dynamic ongoing process that endlessly needs analysis and tweaking.

I think 50 years from now Ehrlich’s current predictions will have fared as well as his 1968 predictions, but that is because thoughtful people anticipated possible problems and worked on solutions.