"What exasperates me more and more is the certainty with which so many people pontificate. As I get older, I think every day that, relative speaking, we know less and less. We don’t know, for example, what existed before the “Big Bang.” We don’t know why we have gotten so much fatter as a species. We don’t know what causes many diseases. We can’t cure the common cold. We don’t know why some people get cancer and others do not. We don’t know why the native people of the southwest disappeared during the fourteenth century. We don’t even know why we think the thoughts we do. So, how is it that some are sure they know the root cause of economic crises, that we cannot grasp a social system as complex as capitalism unless we understand that there is a tendency of the rate of profit to fall?"