an unresizeable window

Does any society ever grow more tolerant? That is: Does acceptance of a position or a group hitherto untolerated ever come without the rejection of another position or group previously tolerated?

My suspicion is that the Overton window of any given place and time can’t be resized, it can only be moved. That is, there’s a politico-ethical equivalent of Dunbar’s number, a relatively fixed range of positions that at any one time can be accepted as potentially valid, or at least not-to-be-extirpated. Greater inclusion, if my suspicion is correct, never happens: an extension of toleration in one direction requires a constriction of toleration in the other, in order to avoid social chaos.

I’m sure I’m not the first to say this. But I think it’s important.