Bryan Caplan  

The Sum of All Fears

The world's three smallest mac... Nick Hanauer on Noah Smith...

I didn't think there was anything more to say about infamous doomsayer Paul Ehrlich.  Until he decided to justify his career to the New York Times.  Background:

No one was more influential -- or more terrifying, some would say -- than Paul R. Ehrlich, a Stanford University biologist... He later went on to forecast that hundreds of millions would starve to death in the 1970s, that 65 million of them would be Americans, that crowded India was essentially doomed, that odds were fair "England will not exist in the year 2000." Dr. Ehrlich was so sure of himself that he warned in 1970 that "sometime in the next 15 years, the end will come." By "the end," he meant "an utter breakdown of the capacity of the planet to support humanity."

Okay, here's Ehrlich's side of the story:

After the passage of 47 years, Dr. Ehrlich offers little in the way of a mea culpa. Quite the contrary. Timetables for disaster like those he once offered have no significance, he told Retro Report, because to someone in his field they mean something "very, very different" from what they do to the average person.

In the video interview, Ehrlich elaborates:

I was recently criticized because I had said many years ago, that I would bet that England wouldn't exist in the year 2000.  Well, England did exist in the year 2000.  But that was only 14 years ago... One of the things that people don't understand is that timing to an ecologist is very very different than timing to an average person.

Whenever smart people say things that strike me as absurd, I fear that this is what they're thinking.  But it seems paranoid.  What expert with a shred of integrity would intentionally pull this bait and switch?  Yet we have it from Ehrlich's own mouth.  He wasn't wrong.  Neither did he lie.  He just deliberately used words that meant one thing to him and a totally different thing to almost everyone who heard them. 

Notice that if this excuse were generally permissible, no one could even be wrong, much less dishonest.  The horror! 

True, this hardly proves that Ehrlich's intellectual sin is widespread.  But at least it's an existence theorem.  Some people really are doing the unspeakable.  And given the intense incentives to never confess such activities, a single high-profile confession makes me fear they're widely done.  Ehrlich makes me feel like an epistemic germaphobe.  Invisible corruption really could be swirling all around me...

COMMENTS (21 to date)
Alex writes:

"One of the things that people don't understand is that timing to an ecologist is very very different than timing to an average person"

Does the word "different" mean the same to him than to the average person?

Maybe he is saying that timing is actually the same!

david condon writes:

That he is still doing this even when the error is blatant and obvious should be quite scary. It leaves a lot of room for people to do so under circumstances when the error is not so obvious. And then there is the possibility Ehrlich is also lying to himself. A serious danger indeed...

Tracy W writes:

Huh! I know a fair few geologists and the like thanks to my mother, and they certainly think of millions in years but have no problems translating.

Tom Papworth writes:

Just to be clear, is he saying

"1) I know it is going to happen soon (in geological terms)
2) I know that geological eras are incomprehensively vast for most people, therefore
3) I will just say "14 years" because their small minds can cope with that"


If so, that's not only hugely arrogant, it's also totally self-defeating. Who now would believe any prediction he made?

ThomasH writes:

This is the Krugman critique of those who opposed fiscal and monetary stimulus in 2008-2009 by predicting inflation. People need to a) specify the conditions pertaining to their predictions and b) be called to account for the outcomes.

Dick White writes:

This Paul Ehrlich story reminds me to ask why it is that economists, who I view generally as well grounded in reality, e.g., free trade is beneficial, do not rise up as a group against the climate change learned community. These pedigreed scholars have been consistently wrong much like Ehrlich and yet the world at large doesn't reject their continued predictions. Indeed, the regard in which they are held seems to have an inverse relation to their inaccurate results.

Njnnja writes:

This sounds very much like a Motte and Bailey Doctrine. An argument is made that sounds very extreme, and that the advocate would very much like to be true ("Unless we change our ways, Britain will cease to exist soon!"). But it is an indefensible argument, so when pressed at all, the advocate falls back to a much more defensible and less controversial argument ("I meant 'soon' in the scale of geological epochs.")

Don Boudreaux writes:

Nice post, Bryan.
It seems to me that the most obvious question to ask Ehrlich is this one: "Does 'the year 2000' mean something different to ecologists than it does to non-ecologists?"

Richard writes:

I didn't read it that way. What I think he was saying

So I said 14 years? Whatever. 14 years, 114 years, to an ecologist, the point is this disaster is going to happen. 14 years was my best estimate at the time, but what you have to realize is, there was a very large margin of error. Focus on what is going to happen, rather than quibbling about dates, which don't mean much when we're talking about the potential for the end of life on earth.

It still sounds pretty stupid, but you can argue that if this is what he meant then he wasn't intentionally lying, since he did believe he was giving the best estimate he could at the time.

But by not including a huge caveat, it's at least lying by omission.

Jeff writes:

If his goal was to get people to have fewer kids and consume fewer resources, then to the extent his scaremongering aided those goals, I would guess in his mind it's simply a matter of the ends justifying the means. As such, he feels no need to apologize or admit error. No muss, no fuss.

But that makes me wonder, though, why he didn't just say something like "yeah, my predictions turned out to be wrong, but they turned out to be wrong in part because people listened to what I was trying to warn them about. Birthrates have fallen, cars are more fuel efficient, etc." Not that this would be convincing, exactly, but it'd be more convincing than what he actually said.

Allen Jacobs writes:

Well put Bryan.

You could also write much the same column about the LIMITS TO GROWTH book in the 70's that was a best seller. It was the World Dynamics Group and Jay Forrester was the proponent chief modeler and writer, although the book LIMITS TO GROWTH was sponsored by the "Club of Rome."

All their scenarios showed collapse within 20-40 years.


NZ writes:
...timing to an ecologist is very very different than timing to an average person.
In a Just and Righteous world, this would trigger a lot of jokes comparing ecologist time to CPT, etc.

Anyway, it's obvious he should have admitted he was wrong about the dates and stuck to defending the substance of his warning. What puzzles me is why he didn't, because I think the substance is actually fairly strong: we should be mindful of overpopulation and resource scarcity and what these things mean for the lifestyle an average person can afford.

My suspicion is that he doesn't have a rigorous conceptual framework that takes into account human biodiversity and culture, and that he's looking mainly at endgame indicators like the availability of food and clean drinking water, rather than other things that might serve as early warning signs of imminent overpopulation. It doesn't happen overnight, after all.

So when his prediction turned out wrong he just sat there baffled.

Bill writes:

[Comment removed for ad hominem remarks and irrelevance.--Econlib Ed.]

hanmeng writes:

Speaking as an average person, I think I've got it.

What an ecologist says means something "very very different" than what it means "to an average person". So he's telling me that I should take whatever he says as meaning something other than what it seems to. And average persons should take whatever he says with a handful of salt. But that includes the statement that what an ecologist says means something very very different than what it means to an average person. So he didn't really mean that either?

Seth Giertz writes:

This seems similar to the behavior documented in When Prophecy Fails:

dbp writes:

"One of the things that people don't understand is that timing to an ecologist is very very different than timing to an average person."

I suppose this would be a fair point if he made these predictions exclusively in esoteric Ecology journals. But he made these predictions in popular books written for the layman, so he really has no excuse.

My hypothesis is that Ehrlich may have exaggerated but really thought doom was right around the corner. Now that his predictions are laughably wrong, he is brazenly lying about what he really believed.

He should be a national laughing stock but he isn't in the usual places: A couple of year's ago at the University of Vermont (where I used to work) he gave a talk and got a hero's welcome. Crazy-wrong predictions will never queer the deal for the hard left.

Bill writes:

The fact that Ehrlich paid Simon on their famous wager concerning changes in resource prices over a specified time horizon was an admission by Simon that he was wrong, at least in that instance.

Scott Sumner writes:

Many (most?) intellectuals are like Ehrlich, except in one respect. Ehrlich is extraordinarily incompetent at covering his tracks.

Michael Byrnes writes:

I think there is a sense in which Ehrlich is correct.

The problem is what dbp said. The specific statements that he now disavows (or sort of disavowed) are what got him his public recognition and notoriety.

If he had constrained himself to more scientifically appropriate statements that took the undertainty he hints at into account, "The Population Bomb" would not have been a best seller, he would not have been a frequent guest of Johnny Carson on The Tonight Show, and basically no one would know who he was.

ThomasH writes:

Crazy-wrong predictions will never queer the deal for the hard left

Or the hard anything.

Tracy W writes:

If you're right then he was lying. He had his best estimate in mind, but instead of saying his best estimate, he instead deliberately said something he didn't believe: an absolute statement.

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