I was thinking about the two-party system in USA and comparing it to mostly multi-party systems in Europe and was wondering, if this national state of democracy is mainly caused by political decisions of a minor group, societal culture or historical developments (wars, cultural assimilation).
I'm not interested in the pros and cons of two-party vs. multi-party systems, you can read this on wikipedia. But do political historians see identic and common explanations for different nations, why they developed towards two-party systems?
Interestingly, I dont know a two-party system evolving towards are multi-party system, while the reverse situation seems to be more common. Of course, one important reason for the two-party system of republicans and democrats in USA is the american civil war, so in what time scales do political historians think and try to analyse politcal developments, what phenomenological criterions (linguistic, cultural, ethnological, political diversification in a distinct society) do they compare to judge, what factors will strengthen a political development towards a two-/multi-party system?
I reformulated the question a bit to falsify the hypothesis in the title and to focus on easier to find out negativ cases, where we have a long and established two-party system today, but no long substantial & longer civil wars in the past splitting the society politically. As quant_dev commented, Britain would be another example of such a historical development.