You argue that the major defining factor of population size is food limits. Australia (to give an example), currently has a birthrate less than 2 births per woman. We have an overall annual immigration, so our population is growing, but if we had no immigration, our population would be decreasing. Australia is a fairly affluent country: plenty of food, people are educated, well supported with social services, and generally feel secure. They don't need the added security of a large family (I don't claim that this is causal, but believe it may have some impact). This seems proof that it is at least possible to disconnect population growth from food supply (and then be able to decrease food supply due to decreased demand). You answered this in response to Q&A 122: "the country has traversed the "demographic trap" and gotten through the growth phase of the population dynamics".
Obviously, as you have pointed out, there's plenty of food in the world, and if it were (able to be) shared out equitably, then no-one would starve. This being so, wouldn't the best course of action be, after figuring out the relevant system dynamics, to attempt to give those in the highest population growth areas the same security we in the affluent, and low-population growth, minority world have? This might include immediate food aid for a period or, preferably, some kind of "food asylum", which might lead to an immediate population spike, but a combined approach of social support services and education, seems like a population growth control method that is more than equitable, just might work, and doesn't seem like a "sci-fi fantasy", as you label other birth control schemes.
As an aside, what do you think of permaculture? Seems like a way of at least starting to break the food lockup, and something that doesn't rely on some kind of fascist revolution.
(This was originally posted on the Ishmael.org guestbook)