Since Chaucer sets The Canterbury Tales at a time of economic transition in England, in which new mercantile and artisan classes are shaking things up for the more traditional "estates" of those who pray, those who fight, and those who work (clerics, nobles, serfs), you can bet that class is going to be a big issue in the Tales. It's most important in the portraits of members of these new classes like the Merchant or Tradesmen's. These portraits explore the source of these pilgrims' wealth and the way they (and their families) are dealing with their newfound social status. One of the most important questions this new class raises is what qualifies someone to have a position of power in their community. Is it only wealth, as seems to be the case when these men ascend to important positions in the government, or is something more "noble" required, as traditionalists would have us believe? The contrast between members of the new and traditional social classes allows The Canterbury Tales to explore this question. (See "Setting" for more on the historical context of the Tales.)
The conflict between pilgrims in The Canterbury Tales reflects the ongoing class conflicts between new and emerging versus traditional classes in the late medieval period.
The portraits of the lower-class pilgrims in The Canterbury Tales agree with the late medieval stereotype that lower-class people are "all brawn, no brains."
The portraits of the lower-class pilgrims in The Canterbury Tales complicate the late medieval stereotype that lower-class people are "all brawn, no brains."