Here the Earl continues the critique of the previous section. Having claimed that the philosophers of self interest are betrayed by their genre—if they sincerely believed that humans acted solely out of self-interest, they would not write their books, but instead exploit this fact—he moves from their writing to the concept of nature. The Earl rarely goes point for point in his arguments: he thinks in pictures and systems. Always delighted and delightful, he cannot pin down a principle to be used in an argument, because principles change into their opposite.
If there is a guiding principle, it is complexity and variation: there is no “Alphabet of Ideas” [Leibniz] where each thought can be broken down into a set number of parts. “
YOU have heard it (my Friend!) as a common Saying, that Interest governs the World. But, I believe, whoever looks narrowly into the Affairs of it, will find, that Passion, Humour, Caprice, Zeal, Faction, and a thousand other Springs, which are counter to Self-Interest, have as considerable a part in the Movements of this Machine. There are more Wheels and Counter-Poises in this Engine than are easily imagin’d. ’Tis of too complex a kind, to fall under one simple View, or be explain’d thus briefly in a word or two. The Studiers of this Mechanism must have a very partial Eye, to overlook all other Motions besides those of the lowest and narrowest compass. 
The Earl does not try to save kindness, or decency, from the clutches of Hobbes and the “lower Genius” descendants of the atomists. His argument is actually simpler: the world is complex, not simply in its arrangement, but in the parts and forces that make it up. A simple theory is a bad theory, because it does not do justice to nature: “Modern Projectors, I know, wou’d willingly rid their hands of these natural Materials; and wou’d fain build after amore uniform way”. There is a naïve and mildly intoxicated perspectivalism at play: no one perspective can catch the machine. Any pretense to see the whole mechanism is not philosophy, but projection–meaning not a film projector, but one who plans, schemes, forecasts, or throw something forward.
More hucksters than hacks, simplification of nature—a concept with “so little meaning”—costs them dearly. The attempt to draw a firm line between Nature and Civil Society (as if the first is automatic, and the latter “a kind of Invention, and Creature of Art”) is doomed. This sort of bifurcation requires that we ‘exit nature’, into some kind of social contract, but with a such a uniform picture of nature, the tools required to exit it will never be available.
Simply put: the social contract is a kind of promise, but it is a promise made in the state of nature. So, either promises are binding in the state of nature (which means there is something already social there) or, they are not, and are stuck there. “A Man is oblig’d to keep his Word. Why? Because he has given his Word to keep it.” In other words: there are obligations, even in nature—here I see shades of Mendelssohn: the political and moral are not imposed by a sovereign fiat, but tended to, and you cannot grown something without a seed; we never begin at the beginning—and civil society is just a further development of a natural form, what Shaftesbury calls “herding”, or forming groups.
What does this have to do with comedy? Humour is one mechanism among many for the development of a civil society: it is not a social product, or social corrective, but rather a primitive force, or building block. It is found in both nature and civil society
As a basic force, it is neither good nor evil: the Earl does not value in this way. Instead, he sets the machine turning, and follows it. The desire for fellowship can lead to conspiracy or “cantonizing”—the need for fellowship can turn into war, a situation that manufactures closeness. Despite being a defense of humour, the essay does not present humour as a good, or value, but an overlooked element of the machine.