While not a student of Toynbee AFAIK, Carroll Quigley worked from Toynbee's theories in The Evolution of Civilizations with a lengthy discussion of the state of Western Civilization. This was written in 1961 with a second edition in 1979, so also predated the end of the Cold War. However he made some predictions for what stage Western Civilization is in that might be of interest.
He observed that while most other civilizations followed the path of growth to empire and then to inevitable decay, Western Civilization has differed in that it has "gone to the brink" of empire multiple times only to shift itself back into expansion. He draws the following periods for Western Civilization:
- Mixture (370-750 AD) Grecoroman + Christianity + "Barbarian"
- Gestation (750-970)
- Expansion (970-1270) Feudal system, guild economics
- Conflict (1270-1440) Hundred Years' War and economic institutionalism
- Expansion II (1440-1650) Renaissance, commercial capitalism
- Conflict II - (1650-1730) Imperialist wars, class conflict
- Expansion III - (1730-1890) Industrial revolution, financial capitalism
- Conflict III - (1890-??)
He ends his book leaving #8/9 an open question:
At the present time it is too early to judge if the present crisis of
Western civilization will resolve itself into a new, fourth Age of
Expansion, or will continue through an Age of Conflict to a universal
empire and ultimately to decay and invasion.
I think Quigley's treatment of the 20th century is a bit weak; he was in the midst of it when he wrote his book, and of course could not see the outcomes of the things he worried about. However, to carry his thinking forward we might complete the table with:
8 Conflict III - (1890-1945) World Wars
9 Expansion IV - (1945-?) Information revolution, globalist capitalism
Quigley's definition of a Stage of Expansion are (a) increased production of goods; (b) increase in population; (c) increase in geographical extent through exploration and colonization; (d) increase in knowledge. I think we can safely say the 2nd half of the 20th century has fulfilled all of these (with space exploration sort of satisfying (c)).
His alternative was that Conflict III would be followed by an Age of Universal Empire. The requirements for such a period are (a) Political domination by a single state (the USA in this case), (b) universal peace and (apparent) prosperity, (c) little economic expansion, (d) no new inventions, (e) vested interests have triumphed and waste capital building blatant monuments.
I think at the end of WWII there was a window of opportunity where the USA could potentially have taken direct control over much of Europe and East Asia, and if so we might have seen something like that. But instead it rebuilt those countries into independent democracies and allowed them to pursue their own economic growth and new inventions, and invested its peace dividend into education, the space race, various wars, creating the Internet, etc.
Where are we right now? Are we still in a growth phase? One could argue that 9/11/2001 marked a turning point into an Age of Conflict, what with the wars in the Middle East. Economically we certainly seem to be on shaky ground, with class conflict and irrationality in politics - all characteristic of Conflict. Further, you could argue the growing dominance of multinational corporations across all aspects of society, including food, materials, journalism, and even the military represents an institutionalization of our instrument of expansion; a pre-condition for Quigley's Conflict period. The recent bubble collapse has left many in the situation of leaving less to their children than they themselves started with; another Quigley pre-condition for Conflict. We're investing less in education, leaving future generations with fewer tools to ensure continued growth. Global warming is disrupting food production in the near term, and drinking water supply in the long term. Wealth is more concentrated in a smaller percentage of people, and that wealth is increasingly locked up in unproductive savings rather than being re-invested.
But it's possible these things just seem dire due to their proximity to us. Recent wars haven't been for territorial expansion, as would be the case with traditional imperialist warfare, and haven't been the civilization-wide struggles that the world wars were. It seems like we get about 100 years of expansion between Conflicts, so what we're seeing today may be just precursors of what's to come in a few more decades. More optimistically we could consider the significant discoveries and developments with solar power, natural gas fracking, robotics, and genetics as promising new avenues of growth for our future; if we can accelerate those developments maybe it'll push us back more deeply into growth.
It'll probably become clearer in a couple hundred years.