I think, an interesting question in this context is whether rationalism is actually growing or not; today we may have more freedom to be rational (after all, some of of the smartest people of previous ages were quite irrational), but are we, as a species, actually getting better at this? It seems that common knowledge (say, that the earth revolves around the sun) has been dramatically improving, but rationalism itself? A good second question would be what would be a good, operational way to measure this...