I have thought a great deal about this subject. To me, it is nearly impossible for us to create an outline of what rights we can create and protect because the number of rights a “free” society should provide should be innumerable. Therefore, it is far easier to focus on the concrete and knowable rights that must be infringed upon to protect the individuals of a society. In the Libertarian community there is a strong fascination with what is called the Non-Aggression Principle. A government should protect all the rights individuals can have that do not violate the Non-Aggression Principle, which simply means anything found coercive to the individual. In this framework, one could argue that we must be tolerant of those who would themselves be intolerant as long as their intolerance is restricted to their personal choices, and does not infringe upon the rights of others.
Ultimately, who is more tolerant? A bigot who will not do business with someone of another group because of some preconceived discriminatory assumption, or a person who wishes to force said bigot to do something against their will in the name of “tolerance”?
To me, the next step in the evolution of Tolerance would be to accept those who are intolerant as long as they can agree not to force their intolerance on others. We do not need to be accepted by the intolerant to, ourselves, accept them, and tolerate them. Ultimately, we are the intolerant ones if we cannot tolerate someone else wishing to have boundaries for themselves. To be tolerant, we must tolerate the intolerance of others.
I’m guessing my view won’t be very popular. It isn’t the easiest, or most appealing, belief that we must love even our enemies. Then again, there are some we may consider “enlightened” who preached love for our enemies.