Tolerance is part of the self-definition of democratic societies, one of the major foundations underlying secular democracy’s sometimes unstated and always ambivalent claim to represent a higher form of civilisation. The transformation of tolerance from a type of indulgence to a type of virtue is explained in part by what it does. It helps to preserve peace in societies with a high level of ethnic and religious diversity, and it has also played an important part in eliminating the injustices that religious and racial minorities suffered when Western societies were more homogenous. Historically, intolerance has extended in extreme cases to persecution, segregation, violence and mass-murder. In more “normal” situations it has usually meant denial of civil and political rights and unequal treatment at law. A fair and decent society is obliged to address this injustice, not least by state and judicial action against groups which refuse to respect the freedom and rights of other people. Problems arise, however, when even groups which respect the freedom and rights of others, such as the Christian churches, are accused of discrimination and treated as intolerant for observing legitimate distinctions; for properly exercising a preference; and for defending the rights of others. In these cases the concept of intolerance, understood as a refusal to respect the rights of others, has been extended to encompass something which is not a form of intolerance at all; namely, the right we all have to refuse to validate choices with which we disagree. This article is available in Solidarity: The Journal of Catholic Social Thought and Secular Ethics: http://researchonline.nd.edu.au/ solidarity/vol1/iss1/1 The Puzzle of Intolerant Tolerance