Though freedom is desirable, Rousseau agrees with Montesquieu that it is not possible in every environment. The government of a state does not produce any goods itself, and so must live off the surplus produced by the people. The closer the relationship between the government and the people, the less the taxes levied by the government will hurt the people. Democracy can survive where there is little surplus and monarchy thrives where there is a great surplus. Thus, Rousseau suggests that climate determines government to a great extent. Colder, northern countries have little surplus and can support democracy, while hotter, southern countries have great surplus and support monarchy. In hot climates, people tend to eat less, have more fertile soil, and need fewer people to work the land. Because fewer people are needed, the population will be more spread out, making them easier to govern. All these considerations serve as evidence that monarchical government thrives in hot climates.
Considering the many disputes regarding what makes a good government, Rousseau suggests that the objective and easily calculated factor of population is the best measure. Political associations exist in order to ensure the protection and prosperity of their members. A growing population is a sign of prosperity, and so a sign of good government. Peace, culture, and other factors are nowhere near as important.
The government is inevitably at odds with the sovereign, and the friction between the two can cause the government to degenerate. Either the government will contract--going from democracy to aristocracy or from aristocracy to monarchy--or the state itself will dissolve. The state dissolves into anarchy when the government usurps sovereign power. Such usurpation breaks the social contract so that citizens become free of their social obligations only to be subjected by force.
The friction between government and sovereign is bound to destroy all states eventually. States, like humans, are only mortal, and Rousseau notes that even Sparta and Rome (his two favorites) devolved after a time. The longevity of a state relies on its legislative power: if the laws are upheld for a long time, they become strong with tradition.
Rousseau's peculiar analysis of the effect climate holds on government rests on a certain picture of production and consumption. Each individual needs to consume a certain fixed quantity of goods--food, clothing, etc. However, each individual does not produce these goods equally. While farmers and tailors produce food and clothing, government magistrates produce nothing of the sort. According to Rousseau, then, the farmers and the tailors are responsible not only for producing sufficient food and clothing for themselves, but also producing enough to take care of the government.
Rousseau is a bit vague in his formulation, and we could read this as a simple endorsement of capitalism: magistrates get paid a certain sum for serving in government, and they can use this money to buy food and clothing for themselves. Magistrates get paid taxpayers' money, each citizen paying taxes that are proportional to the profit he makes from whatever business or trade he undertakes.
However, Rousseau tends to speak negatively about finance and profit motives, so it is more likely that he is thinking along the lines of the Marxist slogan: "from each according to his ability, to each according to his need." Farmers will give up a certain amount of their food, not for the sake of profit, but simply because they produce more food than they need and they recognize that their surplus food is needed to feed government magistrates.
If this is what Rousseau means, he is making the rather naive assumption that the quantity of goods produced will remain fixed regardless. History suggests that workers who have nothing to gain personally from producing a surplus will be less diligent in producing that surplus. Capitalism and consumerism have had such astonishing success (we will leave aside the question of whether this is for the better or worse) because everyone has the direct incentive of profit to increase productivity. When no such incentive exists, productivity tends to decline, and the surplus becomes smaller. Rousseau lists a number of factors that determine the size of a surplus, but does not seem to consider that productivity depends heavily on how the goods are distributed.
Rather than discuss economics, Rousseau discusses climate, and the kinds of soil and people found in different lands. Rousseau concedes that there is obviously no direct correlation between what degree of latitude a state occupies and the kind of government it has, but he also interestingly asserts that the actual facts of the matter have little bearing on the truth of his theory. Even if the south were filled with democracies and the north with monarchies, his theory that hotter climates tend to produce monarchies would still hold: it would just mean that the other factors he discusses outweigh the considerations of climate. This bold assertion raises two questions: How, then, could his theory be proved wrong? And what kind of theory is it? It would seem that he considers this theory to be a self-evident truth. However, it is rather unsatisfying that those of us who might dispute it are given no grounds to raise an objection. His discussion of climate seems to be less like a theory and more like blind dogmatism.
One might also think it odd that Rousseau claims that democracy thrives on a small surplus, but monarchy relies on a large surplus. If there are more magistrates in a democracy, there would be more mouths to feed in government, and so a larger surplus would be needed. However, in this case, Rousseau is quite astute, noting that the determining factor is not the size of government, but how efficiently goods are cycled through society. In an absolute monarchy, the king consumes all the surplus, and the people receive nothing in return. In a democracy, the people who work are the same people who enjoy the benefits of the surplus, so even if this surplus is small, they still do well.
Lastly, one might be puzzled by Rousseau's assertion that population growth is the best and only means of determining good government. Throughout the Social Contract, Rousseau goes on and on about the importance of freedom and equality, and yet here he suggests that prosperity as reflected in population growth is more important. We should note, though, that he is talking about what makes a good government, not what makes a happy society. In fact, he goes on immediately afterward to point out that government and sovereign are in constant conflict and will ultimately pull the state apart. If the population is healthy and the state is prosperous, the government in power is likely to remain happily in power whether it ensures the freedom of its people or not.