One way or another the subject of tolerance - or the lack of it - always hovers around social and political issues. Whether it is the treatment of certain demographics, or immigration, or foreign policy in general, even if not articulated explicitly it remains the elephant in the room.
What effect tolerance and its opposite have can be examined away from the ethical and emotional by considering what these functionalities mean in terms of human activity systems.
Our current perspective is based on affinity relationships and how they come into being. As their name implies, they represent connections made possible by the content of representative states of the system's members such that a degree of synchronicity exists. The label 'member' can refer to neurons in the mind of an individual, they can equally stand for the citizens in a society. Right now we are dealing with the latter.
Any content, imported via the senses, turns into representative states. These states are unique to a given domain (a cluster of members) and, in a very real sense, define it. Any similarity between one domain and another in terms of their respective representative states produces an affinity between the two. Since any domain with its members is an importer of information as well as an exporter, not only do the internal states determine the quality of further information processing but so do any affinity relationships.
Processing means traversal across the members, and the greater the similarity between two or more domains the higher the probability the processes during the traversal will contain content from the entire set. Or, put another way, the higher the probability the traversal will include the set of domains and their members. All things being equal, the traversal will proceed along the path of similar content (higher degrees of similarity being favoured). However, representative states being merely representative, anything that modifies the states of some other domains can bring the latter within reach of the former, because both have become affinitive with each other.
For example, drugs that change the chemical metabolism among neurotransmitters can have the effect of producing associations that otherwise would have been unlikely if not impossible. Depressants modify the pathways such that negative connections, that is to say domains representative of what is perceived as negative by their host, possess a higher degree of probability of being traversed during processing and/or access than those being representative of more positive content. The converse is true in the case of stimulants.
Let us now focus more closely on our topic. A society that displays a certain measure of intolerance does so because within its sumtotal of perceptions, values and priorities it discriminates against manifestations that it sees as a sign of opposition to its nature. Since intolerance needs to be exercised for it to be recognised as such, that society will pro-actively seek out reasons to act out its attitude.
Note that affinity does not need something directly similar; it equally responds to the opposite (just as 'light' indirectly defines 'dark' and 'wet' indirectly defines 'dry').
Therefore, to understand what an intolerant society dislikes one only has to find out what it favours, and vice versa. In other words, what makes an intolerant society raise its opposition is as much part of its affinity envelope as are its values.
For that reason an intolerant society will interact - albeit antagonistically - with those sections it considers as, well, intolerable.
A tolerant society on the other hand sees no inherent reason to engage with different sections since the affinity relationships as described above do not hold. While there is no direct reason to engage, likewise there is no direct reason not to either.
If interaction engenders a certain familiarity and knowledge (due to the likelihood of traversals), we can expect an intolerant society to have more information about its disparate sections than a tolerant one. Note however that an antagonism does not preclude presumption, especially if driven by a need to distance oneself. How much that last factor influences the quality of information about the 'other' that is admitted into a domain is also a function of ideological intensity overall. (In this context it should be remembered that no society can be identified in terms of a single aspect only)
Examples of these relationships are not hard to find. Consider the reasons given for some intolerance towards a demographic or a custom by those who have come into contact with them, compared to the assumptions about the same held by those whose experience does not include a similar exposure. The difference can also be observed in arguments that arise when both sides seek to justify their opinions against each other, using their respective perception to bolster their positions.
In conclusion, having a diverse society does not in itself widen its intellectual scope; just as wisdom is not a direct result of the accumulation of data.