I see where you're coming from, but I tend to think we're entering a permissive phase really. Things like marijuana and gay marriage aber becoming much more accepted. The "dark age" were the 80s and 90s, IMO.
Indeed, cycles can be identified in the History of modern countries, Europe adapting them in a different way than USA. However, I think they don't concern only social issues but also economic ones. And despite this won't please libertarians, I tend to think periods of greater "permissivity" socially speaking tend to correspond to period when Government exerces an important regulation on the economy : Socially left-wing period are also economically left-wing.
The first "progressive era" experienced by both USA, Canada, and Western Europe ran from 1945 to the end of seventies and the beginning of eighties. So I tend to think those cycles last for about 30 years, which means the current economic and social regression is coming to an end.
I think periods tend to be more fluid than that in the United States, & can be loosely seen as corresponding to certain prominent political figures:
1930-1950 trend-left (FDR)
1950-1965 trend-right (Joe McCarthy)
1965-1980 trend-left (Eugene McCarthy)
1980-2005 trend-right (Reagan)
2005- trend-left (Obama)
Along those lines, the trends towards American conservatism/American liberalism could be interpreted as a result of the stranglehold of those ideologies on the American political discourse.
Granted I can't say much about cycles in Europe, though Einzige does have a point that societies trend towards more social permissiveness over time. That should not be too shocking given that social permissiveness in the U.S. has some connection to cities, which I suspect resist the movements to the right to some extent.
