In the beggining of the century there was the epoch of statism, radicalism, and nationalism - this lasted until the 40's. Communism was in vogue, nationalists parties took over many nations, and the free marketers were actually considered the idealists, the statists were thought of as the ones that were good for the economy.
I think the 40's-70's were the epoch of liberalism. It's really amazing to listen to some of the things they considered acceptable in the 70's and how ridiculous that seems today - I mean, imagine someone proposing a 65% tax on top earners to congress today. Proposterous. Even the leftyist of the left can't even find that palatable, and it was mainstream in the 70's.
Now, we're in the epoch of conservatism. Our great social progress movements are coming to a standstill. Even obvious things like gay marriage are getting brushed over by the radical Christian right that owns the nation. Social progress in other countries has stopped as well, and conservative parties are STILL winning everywhere, while all kinds of liberal and libertarian third parties are being drawn off the map in recent European elections. The Democratic party may be coming into play now, but modern Democrats are about as liberal as Reagan - and STILL considered extreme. Also take note, even though Thatcher is out of office in Britian, the modern labour party is actually a bit to the right of the old conservative party.
Does anyone see an end in site?