The patently unremunerative. The diminishing economic returns. The decline of prosperity.

Looking at "breakdown" in Arnold J. Toynbee's work, I neglected to mention what he means by that word. He means the end of the period of growth. In an Editor's Note (page 273) in Toynbee's Study, we find:

In fact we use 'breakdown' in common parlance to mean very much what Mr. Toynbee means when he writes 'disintegration'. But 'breakdown' in this Study does not mean quite that; it means the termination of the period of growth.

... a society does not ever die 'from natural causes', but always dies from suicide or murder -- and nearly always from the former, as this chapter has shown. Similarly the termination of the growth-period, which is a natural event in the history of a living organism, is an 'unnatural' event, due to crime or blunder, in a society; and to this crime or blunder Mr. Toynbee has applied the term 'breakdown' for the purposes of this Study.

Going by the titles of the volumes that make up A Study of History, Toynbee's sequence of stages in the life of a civilization is: genesis, growth, breakdown, and disintegration.

Breakdown: the termination of the period of growth.

Searching the abridged Study of History for Toynbee's use of the word "wealth", I found several instances where the word is used to mean a lot of something, like "a wealth of experience".

I found about half as many instances when Toynbee used the word in the economic sense, like "the measurement of political power: in territory, population, and wealth."

I found no cases where Toynbee used the word to describe the cause of the breakdowns of civilizations. So then I searched for "investment" and "investing". No occurrences of "investment" in the book. For "investing", just one. He gives an example and says the civilization didn't make the investment that a healthy society would have made.

This lack of investment: Was it the cause of the breakdown? A coincidence? A consequence? This is Toynbee's topic. In a memorable paragraph, he writes:

When a civilization is in decline it sometimes happens that a particular technique, that has been both feasible and profitable during the growth stage, now begins to encounter social obstacles and to yield diminishing economic returns; if it becomes patently unremunerative it may be deliberately abandoned. In such a case it would obviously be a complete inversion of the true order of cause and effect to suggest that the abandonment of the technique in such circumstances was due to a technical inability to practise it and that this technical inability was a cause of the breakdown of the civilization.

At least, I find it memorable. Toynbee adds:

An obvious case in point is the abandonment of the Roman roads in Western Europe, which was obviously not a cause but a consequence of the breakdown of the Roman Empire.

"These roads became derelict," Toynbee adds, "because the society which required them ... had gone to pieces."

He offers another example. "In the seventh century of the Christian era," he says, the irrigation system of the Tigris and Euphrates was not repaired, after it 

had been put out of action by a flood which had probably done no more serious damage than many floods that had come and gone in the course of four thousand years.

I like the argument: If the irrigation system lasted for 4000 years, it must not have been flood damage that made it suddenly irreparable. It was the condition of the civilization at the time -- the onset of breakdown, the  concomitant "general state of insecurity", the "patently unremunerative" nature of the irrigation system under such conditions. Toynbee's own view:

This lapse in a matter of technique was in fact not the cause but the consequence of a decline in population and prosperity which was itself due to social causes.

Toynbee goes too easily to "social" causes.

In support of his argument, Toynbee provides on the same page a quote from the historian Rostovtzeff, from The Social and Economic History of the Roman Empire:

The economic explanation of the decay of the Ancient World must be rejected completely. . . . The economic simplification of ancient life was not the cause of what we call the decline of the Ancient World but one of the aspects of the more general phenomenon.

I like Rostovtzeff, so I looked up the quote. Toynbee has it right. I guess I define "economic" different that Rostovtzeff does.  But no: In the phrase "economic simplification" the word economic is only a modifier. The subject of Rostovtzeff's sentence is simplification.

Toynbee puts the emphasis on "economic", as I did initially. Toynbee's emphasis suits his own argument, but it doesn't suit Rostovtzeff's statement. Surely the "simplification of ancient life" is evidence of "the decay of the Ancient World". But the economic simplification of ancient life was just part of the process of simplification. That's Rostovtzeff's point: The economic simplification at that late stage was part of the overall simplification, so the economic explanation of the decay must be rejected. 

But the "decay" is not genesis, nor growth, nor breakdown. Decay is part of Toynbee's "disintegration" stage. The breakdown occurs before the decay. And the economic explanation of the breakdown is a different matter altogether from the explanation of decay and disintegration. So, what caused the breakdown? This is the relevant question.

My answer: The patently unremunerative. The diminishing economic returns. The decline of prosperity. And more significantly, the underlying economic problem that created these other problems: This is the true cause of the troubles.

Rostovtzeff is right: The economic explanation of decay must be rejected. The problem started before the decay, during the breakdown. Or, actually, the problem started even before the breakdown, during the time of growth, and ended up causing both the breakdown and the decline.

Toynbee precisely pinpointed the problem the last time we spoke: the horizontal schism of society along lines of class, because the natural limits on inequality were exceeded; also, other economic imbalances of that nature, imbalances that arise during the time of growth. Imbalances that arise before the breakdown, and long before the decay.

For Toynbee, the horizontal schism appears at the moment of breakdown by definition, because the schism defines and locates the occurrence of the breakdown. But the imbalances that create the schism exist for decades or centuries before the schism appears. The imbalances exist; they grow worse; the growth of the civilization gradually slows. And the imbalances continue to grow worse until a definite schism appears. And then you have the breakdown (the termination of growth). After that, decay and disintegration.

The problems that arise during the growth phase cause growth to slow. They cause the breakdown. And they cause the decay.

The problems can be solved. They must be solved, if the civilization is to endure. This was Toynbee's most important message.