There is a fine line between pluralism and the approval of bunkum, and only a brave and foolish individual is always sure what lies on one side rather than the other. Pluralism is the mark of intellectual seriousness: recognition of the force of a wide range of arguments with which one does not agree. This intellectual tolerance is a rarer commodity than it should be. Both campuses and trading floors contain high concentrations of people with common values and views. The internet and the polarisation of the media have made it easier to confine your sources of information to what you already know, and the opinions you hear to those you already hold.