Thomas Malthus and Population Growth Thomas Malthus's views on population. Malthusian limits.
Thomas Malthus and Population Growth
⇐ Use this menu to view and help create subtitles for this video in many different languages. You'll probably want to hide YouTube's captions if using these subtitles.
- The seventeen hundreds in Europe are often
- referred to as the age of enlightenment,
- it was a time we had come out of the renaissance,
- we'd rediscovered science and reason,
- and in the seventeen hundreds,
- we saw that come about
- with even more progress of society.
- As we exit the seventeen hundreds
- and enter into the eighteen hundreds,
- we start having the industrial revolution,
- and people saw the steady march
- of human reason, of human progress.
- And because of... because of this,
- a lot of people were saying
- 'hey, humanity will continue to improve and..
- and it will improve forever,
- to a point that poverty will go away,
- we will turn to this perfect utopian civilisation
- without wars, without strife of any kind.'
- And, there was something to be said about that
- you had significant improvements,
- in fact you had even more dramatic improvements
- once the industrial revolution started.
- But not everyone in the late seventeen hundreds
- was as optimistic,
- and one of the more famous not-so-optimistic people
- was Thomas Malthus.
- [writes Thomas Malthus] right over here.
- and I will just quote him directly,
- this is from his essay on the principle of population.
- [Quote] 'The power of population
- is so superior to the power of the earth to
- produce subsistence for man,
- that premature death must in some shape
- or other visit the human race.'
- Very uplifting.
- 'The vices of mankind are active
- and able ministers of depopulation.
- They are the precursors
- in the great army of destruction,
- and often finish the dreadful work themselves.
- But should they fail in this war of extermination,
- sickly seasons, epidemics, pestilence
- and plague advance in terrific array,
- and sweep off their thousands
- and tens of thousands.
- Should success still be incomplete,
- gigantic inevitable famine stalks in the rear,
- and with one mighty blow levels the population
- with the food of the world.'
- So not..not so uplifting
- of a little quote right over here.
- But this was his general sense.
- He lived in a time when people were being
- very optimistsic that the progress,
- the march of progress, would go on forever
- until we got to some utopian civilisation.
- But from Thomas Malthus' point of view
- he felt that if people could reproduce
- and increase the population, they will.
- That there's no way of stopping them.
- So from his point of view, the way he saw it -
- so let me on that axis,
- let's say that, that is the population,
- and this axis right over here,
- let's say that.. that is time.
- So by his thinking
- and everything he'd seen in reality up to that point
- would back this up
- that if people had enough food and time,
- they would reproduce,
- and they would reproduce in numbers
- that would grow the population.
- So in his mind the population would just
- keep on increasing.
- It'll just keep on increasing,
- until it can't support itself anymore,
- until the actual productivity of the land
- can't produce enough calories
- to feed all of those people.
- So in his mind there would be some
- natural upper bound,
- based on the actual amount of food
- that the Earth could support.
- So let's say that this is -
- (let me do that in a different colour)
- So in his mind there was some upper bound
- there was some upper bound,
- and once you get to that upper bound
- then all of a sudden
- the vices of mankind will show up and
- if those don't start killing people
- well then all of these other things will -
- epidemics, er.. pestilence, plague and then famine
- people are actually starving to death.
- So in his mind, once you got to this level,
- maybe you had a couple of good crops,
- people are feeling good about themselves,
- they overpopulate.
- But then all of a sudden you have a bad crop,
- or because you have a bad crop,
- people start fighting over resources,
- and wars happen,
- or maybe the population is so dense that
- a plague develops.
- And then you have a massive wave of depopulation.
- And so you would just oscillate around this limit.
- And this limit some people would refer to as a
- Malthusian limit, but it's really just the limit at which
- the population can sustain itself,
- and from Thomas Malthus' point of view,
- he did recognise that
- there were technological improvements,
- especially in things like agriculture,
- and that this line was moving up.
- He had seen it in his own lifetime
- that this line had moved up.
- But from his point of view,
- however far you move this line up,
- the population will always compensate for it
- and catch up to it
- and eventually get to this Mathusian,
- eventually get to this limit and then the same kind of
- not so positive things that he talks about
- would actually happen.
- And some people now say
- 'Oh Thomas Malthus, he was so pessamistic,
- he was obviously wrong, look at what's happened,
- we have so much food on this planet right now,
- we've gone through multiple agricultural revolutions'
- And they are right, in the last two hundred years,
- since Malthus or since the early eighteen hundreds
- we really have been able to outstrip population.
- So this line, this line up here, has been moving up
- much faster than even population.
- So right now we actually do have
- more calories per person on the planet
- than we've had at any time in history.
- But it's not saying that Thomas Malthus was wrong,
- it's just saying that maybe he was just a little bit, er,
- he was a little bit pessimistic
- in when that limit will be reached.
- Now the other dimension where you might say that
- he was maybe wrong,
- was in this principle that
- a population will increase if it CAN increase,
- that if there IS food and there IS time,
- people WILL reproduce.
- And a good counterpoint to that is
- what we've now observed
- in modern developed nations.
- And so this right over here shows
- the population growth.
- I got this from 'The World Bank',
- that the population growth
- over some modern developed nations.
- You can see that the United States is pretty low
- but it is still positive,
- it's still...well, it's still over half a percent in,
- but even that adds up when you compound it.
- But if you look over here, Japan and Germany,
- and Japan and Germany have
- less immigration than the U.S,
- especially Japan, they are actually negative.
- So just this population left to its own devices
- especially if you account for people
- not going across borders,
- just the population itself growing,
- they actually have negative growth.
- So there is some reason to believe that
- this is evidence that Thomas Malthus was wrong
- or not completely right, he didn't put into account
- that maybe once a society becomes rich enough
- and educated enough,
- that they might not just populate the world
- or have as many kids as they want.
- They might try to do other things with their time
- whatever that might be.
- So I just wanted to expose you to this idea
- time will tell if Thomas Malthus
- if we can always keep this line,
- if we can always keep this line of food productivity
- growing faster than the population;
- and time will tell whether our populations can become
- I guess we could say, developed enough
- so that they don't in excrib (I can never say that word)
- [execrably], they don't always just keep growing,
- maybe they DO become a Japan or Germany situation
- in the world population,
- especially if we have a high rate of literacy,
- eventually does level off.
- So that it never even has a chance of
- hitting up against that Malthusian limit.
- But though I would introduce you to the idea
- and now you can go to parties
- and you can talk about things like Malthusian limits.
- And if you wanna know what country, you know,
- is maybe closest to the Malthusian limit right now,
- and we've talked about this before,
- but a good case of example is something like
- Bangladesh. They are right now the
- most population-dense country in the world,
- they have nine hundred people per square kilometre.
- And just to give you a sense of perspective
- that's thirty times more dense than the U.S is.
- So if you took every person in the U.S
- and turned them into thirty people in the U.S
- that would give you a sense of
- how dense Bangladesh is.
- And it's probably due, to a certain degree
- that it is very fertile land,
- it's the river delta of the Ganges
- essentially makes up the entire country,
- but they do, they've had in the past had famines,
- they gotten a little bit beyond that,
- but still you do have major problems
- with the flooding and the resources.
- So hopefully they'll be able to er,
- they'll be able to say ahead of the curve.
Be specific, and indicate a time in the video:
At 5:31, how is the moon large enough to block the sun? Isn't the sun way larger?
Have something that's not a question about this content?
This discussion area is not meant for answering homework questions.
Share a tip
When naming a variable, it is okay to use most letters, but some are reserved, like 'e', which represents the value 2.7831...
Have something that's not a tip or feedback about this content?
This discussion area is not meant for answering homework questions.
Discuss the site
For general discussions about Khan Academy, visit our Reddit discussion page.
Flag inappropriate posts
Here are posts to avoid making. If you do encounter them, flag them for attention from our Guardians.
- disrespectful or offensive
- an advertisement
- low quality
- not about the video topic
- soliciting votes or seeking badges
- a homework question
- a duplicate answer
- repeatedly making the same post
- a tip or feedback in Questions
- a question in Tips & Feedback
- an answer that should be its own question
about the site