How did the Black Death free the serfs?

[Jonathan]

The theory would go that although the population might have simply returned to an earlier level, the economy in, say, 1350 was not what it had been in 1150. The centuries of population growth and general prosperity from 1000-1300 had resulted in the appearance of many new cities, more industry (particularly in textiles), and trade. With so many dead and so many people trying to rebuild, laborers had a lot more options to choose between. In a sense, of course, those options had been there all along, but now there was less competition with other peasants for them.

From the perspective of the lords and merchants, however, it was different. Yes, there were fewer lords owning land, but there was no less land to be worked. Plague among the landowning classes meant that the existing land ended up concentrated in fewer hands by inheritance. So another result of the plague was a sudden boost in Europe's wealth per capita, which may explain Europe's flourishing in the later Middle Ages and early modern period.

It should be pointed out, though, that the evidence for all this is far from conclusive. We don't even know for sure how much of the population was killed by the plague, and the trend toward greater monetization of the economy and greater liberty for peasants was well underway before the plague struck.