One common argument for economic pessimism
stems from the fear of increasing population.
Let's take a look at this argument and see if it's true.
The reverend Thomas Robert Malthus published his famous book,
"An Essay on the Principle of Population," first edition 1798.
This book remains extremely influential today.
In the basic argument, Malthus suggests that there are diminishing returns to land.
That is, if we add more workers to the land
the land produces smaller and smaller amounts of additional value.
This means, for instance, that if population doubles
and we imagine twice the number of people working on the land,
we don't produce twice as much food.
So a doubling of the population would mean
that each person actually has less food than before
compared to the lower population.
Now imagine that a technological improvement comes along
and people are somewhat wealthier.
In this situation there will be, according to Malthus,
a greater number of people.
People will live longer
and they also will have more resources to support a greater number of children.
Fewer children, for instance, will die in infancy.
That means a growing population.
But if you accept Malthus's assumption of diminishing returns to land
and the notion of a fixed supply of land, not all is well.
The growing population means less food for each person.
Over time, the population will shrink again
because there will be less food to support children,
less food to support people in their old age,
and living standards will eventually fall.
The basic point is that, at first, something good happens
then population goes up because of the good news
but in the longer run that new and larger population brings you back down
to a lower standard of living.
Those are the basic mechanics of the Malthusian model.
Just to review those assumptions written down,
there's a fixed and vital factor of production, land,
there are diminishing returns on that factor.
Income determines population growth,
rising wages mean higher survival rates,
but higher survival rates eventually push wages back down.
In the Malthusian model, a lot of policies which might appear to help the poor
actually don't help at all.
For instance, imagine a vaccination program which limits some kind of disease.
In the short run, of course, this will make the poor people healthier.
But in the Malthusian model, in the longer run,
you end up with a greater number of poor people
because fewer of them are dying and living standards collapse once again.
This seems counterintuitive and indeed, as we'll see, it's probably false,
but nonetheless this anecdote is one way of thinking through
what the Malthusian model would actually mean in practice.
There is some evidence that a version of the Malthusian model
may help us explain earlier periods in world history.
For instance, if we take a typical European living standard
during the time of the Roman Empire
and compare it to a typical European living standard
in, say, the year 1700,
it's not clear that there was much progress,
if indeed any progress at all.
Net sustainable economic growth was slow during virtually all of this period
and many regions of the world retrogressed.
We don't have the data to say for sure that Malthus was right about this period,
but, at the very least, the sense we have from the data we do have
is consistent with a Malthusian model.
Since the industrial revolutions of the 19th century,
the Malthusian model seems to be mostly or even completely false.
For instance, take the country of japan,
it really does have a fixed supply of land.
Improvements in technology have kept the Japanese standard of living very high,
well above subsistence,
and rather than just multiplying numbers endlessly,
in fact the birth rate in japan has fallen dramatically.
The population of japan actually is shrinking
and living standards remain high
even though, at the moment, the rate of economic growth is fairly low.
It's interesting, but in 1800 Malthus himself wrote about China and Japan.
And he wrote, I quote :
"From the accounts we have in China and Japan,
it may be fairly doubted whether the best directed efforts of human industry
could double the produce of these countries even once in any number of years."
Of course, what we saw in the late 20th century
is that the economic produce of Japan could double in about 10 years time
and the economic produce of China could double in about 7 years time
and stay there.
On these issues Malthus was quite simply wrong.
What about Africa?
Might the Malthusian model be true for Africa today?
Development economist Charles Kenny set out to study exactly this question
and he looked at data from 46 different African countries.
Keep in mind the Malthusian predictions.
The first is that rising GDP per capita should lead to a rising population.
The second is that a rising population should lead to falling GDP per capita.
But of the 46 African countries Kenny looked at,
those Malthusian correlations were found in only 13 of them
and only in 4 of those 13 cases were the correlations even marginally strong,
defined by Kenny as greater than 0.3.
That suggests that, for the most part,
even for Africa,
the Malthusian model today is false.
The Malthusian model is perhaps best thought of as a kind of challenge
which the world must must face.
But not is a good description of how the world actually works,
at least not today.
For further readings on this topic, you can google "Thomas Robert Malthus".
You can even read Malthus's essay online if you want.
And for the more modern take, using data,
please google "Charles Kenny Malthusian trap".