The paradox of tolerance (1/n)

From Wikipedia (highlights my own): 

Philosopher Karl Popper defined the paradox in 1945 in The Open Society and Its Enemies Vol. 1 (in note 4 to Chapter 7).

"Less well known is the paradox of tolerance: Unlimited tolerance must lead to the disappearance of tolerance. If we extend unlimited tolerance even to those who are intolerant, if we are not prepared to defend a tolerant society against the onslaught of the intolerant, then the tolerant will be destroyed, and tolerance with them. — In this formulation, I do not imply, for instance, that we should always suppress the utterance of intolerant philosophies; as long as we can counter them by rational argument and keep them in check by public opinion, suppression would certainly be unwise. But we should claim the right to suppress them if necessary even by force; for it may easily turn out that they are not prepared to meet us on the level of rational argument, but begin by denouncing all argument; they may forbid their followers to listen to rational argument, because it is deceptive, and teach them to answer arguments by the use of their fists or pistols. We should therefore claim, in the name of tolerance, the right not to tolerate the intolerant."

This is a subject that has come up repeatedly in my discussions with friends and family over the past couple of years. Two distinct societal movements have brought me back to this question:

1. Immigration of societies with different cultural "values" into European societies
2. Feminism and other identity driven groups

In simple terms, the argument Popper makes is that if we aren't all operating by the same set of foundational rules, then a society cannot be fully tolerant without sowing the seeds of its own demise. The argument can be split into the question of what and how are foundational rules established on one side and what constitutes intolerant behavior. 

Starting with the second question (which is the easy one of course), any intolerant behavior can be deemed as behavior that threatens the viability of the set of foundational rules. Using the recent immigration crisis as an example, if we agree that one rule of the set of European/Western foundational rules is "women have the same rights as men", then tolerating migrants that abide by the foundational rule that "women should be the property of men" puts into question the viability of European/Western societies.

So if the set of foundational rules U1 which includes n rules has any rule that is opposite to the set of foudational rules U2 which includes m rules then U1 and U2 are mutually exclusive. Any individual that would want to  adhere to the set U1 cannot at the same time adhere to the set U2. He can though create a new set U3 which includes some rules from U1 and some rules from U2. But this will again be mutually exclusive with U1 and U2. 

Of course, this is obviously the easy part of the argument. The tough parts are 1) how do you identify rules that are part of a set U(i) of foundational rules? 2) how do you communicate those rules? 3) how can those rules be modified?