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The conventional wisdom of demographers is fundamentally flawed.

In the conversation "Why do so many think that population growth is an important issue for the environment? Don't they know the facts of demographics?" Hans Rosling uses the "facts" of demography to argue we don't have to worry about population growth. Demographers have fundamental flaws in their thinking. In short, they are dead wrong.

Consider a belief that has these 2 characteristics: 1) believers average more than 2 children, and 2) they successfully pass along that belief to the next generation to at an average of at least 2 of those children. This belief will overpopulate the planet. Imagine that 99% of the population are non-believers, and 1% are believers. It would take many generations for the believers to rise to sufficient numbers so that demographers would notice them, but in the end, the birth rate will be determined by the believers.

This logic shows us flaws in the data collection and interpretation techniques that demographers use. Demographers must prove that these belief characteristics cannot exist if there is any hope that the downward trend of birth rates will continue and stay at or below an average of 2 children.

Their sampling techniques filter out beliefs that are passed to the next generation. This error means that if demographers tried to find groups that have beliefs that are not behaving according to the demographic transition predictions, they won't find them in their data.

Demographers use extrapolation techniques to predict future birth rates, but the logic dictates that they must find groups that are averaging the most children, and monitor their growth.


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    May 8 2012: But demographers have never said that their projections are 100% accurate. That's not needed either.

    Stating that because 1% of a population of 7 billion may have a birth rate that deviates from projections, and that this is a huge problem for demography -- that's really a silly topic.

    Demographers have been mostly right about population trends. I don't see any reason why their sophisticated statistical techniques would suddenly become invalid because of some strange, opaque little theory about "1% believers".

    I still don't get the point. I'll just continue to read demographers' projections and take them as they are: projections with a high degree of certainty.

    I see a bit of a similarity between what the Climate Change community does: nobody can predict the future, but they can, with varying degrees of certainty, project what will happen. And they come to a consensus, offering a rather clear picture of the trends and threats.

    Demography is not calculating the elliptical track of a planet. It doesn't have to be. It's a ridiculous comparison.
    • May 9 2012: If an astronomer used the projection technique from the perspective that the Earth is the center of all orbits to predict where stars and planets will be, they would be totally capable of positioning a 100x telescope to track anything in the sky for the next several hours. They would be useless for anything more significant, like for example putting a person on the moon, or finding large objects on a collision course with Earth.

      Demographers are in an analogous situation. Their failure to comprehend the concept I describe here, has led to the conclusion that we only need to improve women's education and rights, and ensure access to birth control. The conclusion is that if we do that, the total fertility rate will come down and we will not suffer deaths due to over breeding (listen to the 2 TED talks referenced above). I totally agree that we need to do these things. The logic shown in this topic dictates that those actions are not sufficient to ensure we end deaths due to over breeding.

      In order to end deaths due to over breeding we must all comprehend that a belief with these characteristics is morally wrong, because that is the only way to ensure a belief with these characteristics cannot happen.

      It seems you missed this concept: "I have the right to have as many children as I want" is a belief that has these two conditions and nearly 100% of humans have this belief. I agree that this is a strange opaque theory, but only because you and many others are actively refusing to comprehend it. It is not about 1% believers, it is about 99.99999% of believers. 1% was simply an example number.

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