Dear Ken,(posted 8764 days ago)I see some leaks in your line of argument, and some plugged holes you might not have noticed.
The leak is that Patrick's calculation (I made it earlier than he did, just incidentally) gives 7% as a crazy upper bound, but the point is that it leaves 93% for domestic variables. In other words, if something as small as what Patrick calculates is to be refurbished and set up as some sort of Big Factor, then all kinds of previously ignored domestic somethings are Even Bigger. Do you see the point? It's like the objection to small-big causation: if Small Factor number 87 is to be counted as Big, then all other Small Factors are big, too, and one is left without explanation--or, rather, with too many little ones.
The argument is important because not asking how big is so crucial to attributing great force to foreign trade. Most changes were domestic, yes?
A hole-already-plugged is the logic of seed-yield ratios (which as I understand it are always very low in rice, so wheat-barley-oats has this disadvantage?): a medieval society that was (1.) largely agricultural and (2.) facing yield/seed ratios of 4 or 5 had to set aside a VERY large part of GNP just to get fed next year. It's real saving, tho an extreme case of Uncle Simon's low lived capital--the abstension from consumption is only eight months or so. When yields increase and agriculture becomes less important, on both counts a big portion of GNP is freed for net investment. Say,
(2/3 of a year) times
(1/5 seed set aside per gross yield of grain) times
(50% of GNP which is grain) equals
6.6666% of GNP per year devoted to seed,
which could change to, say, 30% of GNP [in all these I'm trying to bias the case against] and yields of 1/10:
(2/3) x (1/10) x (30%) = 2%, or 4.7% released for net investment.