This is a lovely paradox. If one is truly tolerant, then one must by definition be tolerant towards the intolerant, and therefore to promote a society of tolerance one must allow the intolerant to behave as their nature dictates. That would mean then that issues of intolerance based on race/colour, breeding, education, height, weight, money, etc., must be tolerated by society as a whole. Further, that those who might suffer harm as a result of intolerance would themselves need to be accepting of such intolerance in order to be tolerant themselves.
Can tolerance exist in its purest form as I have just described. Yes it can individually, yet in reality such a purity of tolerance can only fail in society as its laws are in effect intolerant of intolerance, and therefore society itself can only be intolerant regardless of the degrees of tolerance of the individuals that may exist within a society. Thus to a part of your question, it isn't tolerance of intolerance that kills tolerance, but intolerance itself that cannot allow tolerance to exist in it's purest form within a society.
As to arguments for and against intolerance, such would be made based on a society's moral frame of reference. If a society tolerates slavery, it might be able to argue that such slavery is for the greater good of the society in question. Those opposed within such a society might not be able to justify their own individual intolerance towards slavery if they cannot make a compelling argument that fits within the society's moral point of reference in order to show the society itself that intolerance of the tolerable may be necessary.
Personally, I am glad we have an intolerant society, in that it allows those of us who feel more tolerant towards others to have the freedom to do so, knowing that someone else's intolerance has protected my own right to be tolerant! ;-)