People interested in malthusian theories focus on calories
Which is of course total nonsense, as number of calories consumer per capita varies extremely little over huge differences in GDP. some data
So quality of life as measured by things other than food may have become high in 1300, but the famine of 1315-1317 suggests that the food situation was precarious.
Not at all. Even if there's plenty of unused land lying around, if you get unusually low yields, you can get famine. Few civilizations farmed spare land and threw away food, just in case the spare food might be useful, so food margins have nothing to do with availability of free land or lack of it. It takes some time to get new land into use, one year at the very least, more realistically many years to cut forests, build settlements, gather people, animals, and seed and move there, make agricultural tools etc. It's a major project, and conditions of famine do not help at all.
I think the adoption of the high calorie-per-acre potato is correlated with low productivity
Potato was widely adopted in 18th century, the Eastern vs Western divide refers to Late Middle ages/Early Modern period, which took place long before it. During that time Poland and other countries became major exporters of wheat to Western Europe, using particularly nasty forms of serf labour.
No, it just says it about 1000-1250.
That's not what I meant about 1350. Clearly if land was plentiful in 1000-1250, it must have been even more plentiful in 400-1000, and yet population wasn't expanding back to its Roman levels.
Raiders were Vikings / Muslim / Hungarians / etc. and they were raiding entire Europe. There was no distinction between raidable and not raidable lands. Here's map of Viking raids. Other groups raided other regions. Most of Europe, especially coastal areas were repeatedly raided, these lands were definitely inhabited all the time.
We know that in the right circumstances, such as colonial America, population can double each generation.
It can, and also GDP/capita was increasing while population was increasing. For pretty much any country you try. Malthusian theory suggests ridiculously high starting GDP/capita, which would then gradually go down as population increased, which is completely wrong.
People interested in malthusian theories focus on calories
Which is of course total nonsense, as number of calories consumer per capita varies extremely little over huge differences in GDP. some data
I'm sorry if I wasn't clear, but I reject GDP for this purpose. I suspect that Braudel and the conventional wisdom about 1300 are like saying that people today are as kings, for they have the greatest musicians of the century at their beck and call on youtube. GDP tells how nice are the luxuries, but it doesn't tell if someone is starving.
Malthusians claim...
This is an attempt to list all of the possible ways in which humanity may avoid scenarios where the average standard of living is close to subsistence, in response to Robin Hanson's recent series of posts on Overcoming Bias, where he argues that such an outcome is likely in the long run.
I'll start with six, some suggested by myself, and others collected from comments on Overcoming Bias and Robin's own posts. If anyone provides additional ideas, I'll add them to the list.
(I have a more general point here, BTW, which is that predicting the far future is very difficult. Before thinking that some outcome is inevitable or highly likely, it's a good idea to repeatedly ask oneself "This is all the ways that I can think of why it may fail to come true. Am I sure that all of them have low probability and that I'm not missing anything?" There may be some scenario with a non-negligible probability that your brain simply overlooked when you first asked it.)
Singleton
A world government or superpower imposes a population control policy over the whole world.
Strong Security
Strong defensive technologies and doctrines (such as Mutually Assured Destruction) allow nations, communities, and maybe tribes and families to unilaterally limit their populations within their own borders, while holding off hordes of would-be invaders and immigrants.
Non-Human Capital
Maximizing the wealth and power of a nation requires an optimal mix of human and non-human capital. Nations that fail to adopt population controls find their relative wealth and power fade over time as their mixes deviate from the optimum (i.e., they find themselves spending too much resources on raising humans, and not enough on building machines), and either move to correct this or are taken over by stronger powers. (I believe that historically this was the reason China adopted its one-child policy.)
Unlimited Growth
We don't completely understand the laws of physics, nor the nature of value. There turns out to be some way for economic growth to continue without limit. (Robin himself once wrote "I know of no law limiting economic value per atom" but apparently changed his mind later.)
Selfish Memes
Memes that manage to divert people's resources away from biological reproduction and towards memetic reproduction will have an advantage over memes that don't. On the other hand, genes that manage to block such memes will have an advantage over genes that don't. Memes manage to keep the upper hand in this struggle (or periodically regain the upper hand).
Disease, Warfare, Natural Disasters, Aliens, Keeper of the Simulation
One or more of these come along regularly to keep the human population in check and per capita incomes above subsistence.