The paradox of tolerance (4/n)

The final question pertaining to the paradox of tolerance is: "how and when should the incoming society accept changes to the set of foundational rules?"

I don't really think it's a question that our societies have changed massively over the course of history and thereby have accepted new sets of foundational rules relatively often. For instance, prior to slavery being outlawed, the set of foundational rules in European nations included the rule "the white race is superior to other races". I tend to think that both progress in science, showing that hierarchy between races isn't verifiable biologically, as well as changes in the moral landscape, where freedom seemed to be the primary goal, led to the decision to make slavery illegal. Over time, the legal decision has become a foundational rule of our western societies, and there is close to no contest of it.

Using the example above, I tend to think that there are two mutually necessary ways for foundational rules to evolve: scientific progress and universal values.

• Scientific progress: in the event that science can be prove that one of our foundational rules is "false" in the scientific sense, that is unverifiable/unfalsifiable, then it follows necessarily that we should (I insist on should and not will, changes take time) dismiss this rule from our foundational set of rules and come up with a new one, based on a falsifiable hypothesis. 
• Universal values: I like the definition of Amartya Sen on this "universal values are values that all people have reason to believe in, not values that all people currently value". Non-violence is the obvious candidate to universal values (and probably the only clear one) as all individuals have reason to believe in it even if some don't currently.