Category Archives: Science

The insoluble problem of population

The world population is currently more than two and a half times what it was when my parents were born. It can’t keep on growing forever.


One point of view is that as the population continues to grow, technology will grow apace — so that, no matter how high the figures climb, human ingenuity will always find a way to make sure there is enough food, water, oxygen, and living space to go around.

Obviously that can’t be true. Maybe the earth can be made to support a very large number of people — trillions, say — but it can’t support an arbitrarily large number. There must be a limit somewhere. Sooner or later, if the population continues to grow, we will reach that limit.

And long before we reach the point where it is physically impossible for the earth to support us, we will reach the point — many countries have reached it already — where population density begins to have a negative effect on the quality of life. No one wants to live on a planet — or in a country — which is filled to capacity, where there is no extra space, no countryside, no wilderness, not even any backyards or roomy living rooms. Living in Taiwan (with 19 times the population density of the U.S.), I’ve had a little foretaste of that, and it isn’t very nice.

Nor is space colonization a viable solution. Even assuming it were technically feasible, uprooting a few billion people every generation or two and shipping them off to other planets isn’t going to do much for our quality of life either.


Another “optimistic” point of view is that the problem will solve — is solving — itself, as more and more peoples voluntarily choose sub-replacement fertility. In most of the developed world, population growth rates are low or even negative, and what growth there is comes more from immigration than from the reproduction of the indigenous population. And the developing world is, as the euphemism implies, assumed to be developing. That is, given time, it will become “developed” and stop reproducing.

But such a situation is evolutionarily unstable and cannot possibly be permanent. So long as there is variation in fertility rates, and so long as that variation is correlated with heritable (genetic) or quasi-heritable (religious) features, those who reproduce at above-replacement levels will multiply at the expense of those who do not, and overall rates of population growth will go back up.


Since voluntary population control cannot by its nature be a long-term solution, that leaves Chinese-style coercive population control — which is obviously morally unacceptable. To be effective, it would have to be applied to the entire world, and it would have to be strictly enforced — meaning, in practice, forced abortion or infanticide. Without strict, universal enforcement, it would be no more stable than voluntary control. Some people would inevitably go on reproducing, regardless of social pressure or sanctions, and whatever it was that made them do so, they would be likely to pass it on to the next generation — leading in the long term to rising fertility.


So there’s no solution at all.


Filed under Politics, Science

Reading: Brian Greene

  • The Fabric of the Cosmos: Space, Time, and the Texture of Reality (15 Jul 2009)

This is an excellent popularization of various topics in physics — relativity and quantum mechanics, entropy and time’s arrow, cosmology, and various versions of string theory. Greene explains these rather arcane theories very clearly and was able to give me what had previously eluded me — a basic layman’s literacy in contemporary physics.

My only quibble is the plethora of TV-show references, which I found unnecessary, patronizing, and (at least for someone like me, who knows even less about the Simpsons than about physics) distracting. One gets the distinct impression that Greene thinks his readers are a little dumb and are in need of kool pop culture references to help them realize that physics is, like, totally rad. (Steven Pinker’s books are also heavy on the pop culture, but he manages to do it in a non-grating, genuinely entertaining way. I should try to figure out what the difference is between their two techniques.)

Greene’s book also reminded me that some of the ideas I’ve been thinking of under the heading of “anti-solipsism” already have a prefectly good name: relativity. If you accept that all persons and points of view are equally real, then under Einstein’s theories it follows that all points in time are equally real.

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Voltaire asks the right question

Voltaire’s Philosophical Dictionary includes a dialogue between the Philosopher and Nature, in which the Philosopher poses the following question:

We are curious. I want to know how being so crude in your mountains, in your deserts, in your seas, you appear nevertheless so industrious in your animals, in your vegetables?

Nature’s reply is to dismiss the apparent difference (“Do you not know that there is an infinite art in those seas and those mountains that you find so crude?”), but the Philosopher’s question is a good one. However impressive seas and mountains (and stars, and everything else in the universe) may be in their own way, none of it even begins to compare with the astonishing complexity of the biological world. Why this chasm?

Darwinism answers Voltaire’s question. Natural selection is ultimately the only way extremely complex things can come into being, and so every extremely complex thing in the world is created, either directly (organisms) or indirectly (technology created by organisms), by replicators such as DNA molecules. The chasm is between things that were created by replicators and things that were not.

Creationism, on the other hand, can’t really answer the question. (Paley noticed how similar an animal is to a watch and how different it is from a rock — and concluded that animals must have been made by the same guy who invented rocks!) Of course there’s no reason why God can’t have created simple things as well as complex, but creationism doesn’t know what do with the obvious correlation between complexity and reproduction. In nature we find very complex things that reproduce and far simpler things that don’t. Conspicuous by its absence is anything truly analogous to the human technology typified by the watch — very complex things that don’t reproduce. To a creationist, there’s no obvious reason for this; it must just be how God decided to do things. From a Darwinian point of view, though, the absence of true “watches” in nature is precisely what we ought to expect.

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You say revelation, I say hypothesis

Bruce Charlton’s interesting new blog Scientists considering Christianity (the title refers to the intended readers, not to the writer) does not, regrettably, allow readers to leave comments, so I’ll just have to do my commenting here. I should mention at the outset, I suppose, that I myself am neither a scientist nor seriously considering Christianity.

In a recent post called Hypotheses and revelations, Mr. Charlton addresses those who think “that Christian revelation is arbitrary (or made-up) compared with scientific hypotheses or theories.” After describing the way hypotheses often occur to scientists suddenly and inexplicably in a flash of inspiration, he concludes that the formation of a scientific hypothesis is not itself a scientific process, and that hypotheses are no less “made up” than revelations. He closes with this (I’ve proofread it a bit):

My point is that hypotheses in relation to [science] are analogous to revelation in relation to religion — both come from outside of the system, but science is based on hypotheses in the same way that Christianity is based on revelation.

But the point is that in formal terms (in terms of systems theory, to be exact) Christian revelations are no more bizarre than scientific hypotheses. Or both are equally bizarre.

To say that a revelations and hypotheses are “analogous” is actually an understatement. I would go further and say that a revelation simply is a hypothesis. Prophets and scientists come up with their ideas in pretty much the same ways — hunches, flashes of intuition, even dreams or visions (see Kekulé). The choice of words, “revelation” or “hypothesis,” is simply a reflection of one’s opinion about where the idea came from and how trustworthy it is. If you think it came from God and is therefore True, you call it a revelation. If you think it came from God-knows-where but might turn out to be true after being tested, you call it a hypothesis. Revelations are not a category apart; rather, a “revelation” is just a hypothesis you don’t feel the need to test.

When Mr. Charlton introduces the issue — “that Christian revelation is arbitrary (or made-up) compared with scientific hypotheses or theories” — he’s being a little sneaky, lumping hypotheses and theories together. Once he’s convinced you, correctly, that a hypothesis is no more reasonable or “scientific” than a revelation, you’re meant to conclude that revealed religion is therefore just as reasonable as science. But while Christianity has hypotheses aplenty, in the form of “revelations,” it offers nothing as robust as a good scientific theory — that is, a hypothesis that has proven itself through rigorous and systematic testing.

Of course religious people test their hypotheses, too, after a fashion, since they don’t indiscriminately accept every purported revelation (Christians, for example, don’t generally accept the revelation of the Qur’an to Muhammad), but the testing is of a very different — and, it must be said, rather arbitrary — sort. Christianity generally focuses on the source of the hypothesis: Did he have a vision? Did your heart burn within you? Is that in the Bible? In science, on the other hand, the source of the hypothesis is irrelevant. It doesn’t matter whether the hypothesis originated in a hunch, a dream, a bit of wishful thinking, or even in scripture; all that matters is whether it can be tested and how well it passes those tests. If a hypothesis consistently makes true predictions, we accept it, regardless of where it came from; and if it doesn’t, we don’t.

John Dominic Crossan had the right idea:

And only when [the] human normalcy [of “revelation”] is accepted can a proper response be offered. It should not be this: We deny the fact of your vision. It should be this: Tell us the content of your vision. And then we will have to judge not whether he had it or not, but whether we should follow it or not. (The Jesus Controversy, p. 7)

And so did William Blake:

The rat, the mouse, the fox, the rabbet; watch the roots,
the lion, the tyger, the horse, the elephant, watch the fruits.
(The Marriage of Heaven and Hell)

So, yes, Christian doctrines seem arbitrary compared with scientific theories. But the difference lies not in the admittedly arbitrary hypotheses/revelations that provide the raw material for both disciplines, but rather in the differing ways in which hypotheses are tested or validated. — whether by the objective tests of the scientific method, or by the arbitrary ones prescribed by various religions.

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Reading: Jared Diamond

I’ve read one book by Jared Diamond:

  • Guns, Germs, and Steel (4 Jul 2007)

Diamond sets out to explain why Eurasians conquered America, Australia, and Africa, rather than the other way around, without postulating any genetic differences in intelligence or personality among the peoples themselves. (He wants to make money, after all!) He attributes it all to environmental differences — taking care not to notice that, by the logic of natural selection, longstanding environmental differences (i.e., different selection pressures) will inevitably give rise to differences in gene frequency.

Diamond boils the Eurasian advantage down to two basic factors: the east-west orientation of the continent and the presence of many large domesticable mammals. He’s mostly very convincing, though he doesn’t explain very clearly why Africa’s many large mammals are not suitable for domestication. (Zebras, he says, are bad-tempered and like to bite people. Is that really such a huge obstacle, given that the most widely domesticated animal in the world is the wolf?) Overall, it’s a good, thought-provoking read and deepens one’s understanding of world history.

I’m afraid that the one thing from this book that will stick in my mind, though, is its bizarre reference to “a hyena-like animal called an aardvark” that somehow slipped past the proofreaders.

There is, of course, a kind of hyena called an aardwolf, which I assumed must be what he had in mind. But, no, he’s talking about honest-to-goodness aardvarks and the “aardvark melon” they eat.

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