How we cite our quotes: Section.Part (if applicable).Paragraph
Quote #7
In societies for play, there are laws required for the conduct of the game; and these laws are different in each game. The foundation, I own, of such societies is frivolous; and the laws are, in a great measure, though not altogether, capricious and arbitrary. So far is there a material difference between them and the rules of justice, fidelity, and loyalty [...] The comparison, therefore, in these respects, is very imperfect. We may only learn from it the necessity of rules, wherever men have any intercourse with each other. (IV.18)
When societies don't have clear, fixed rules, how do they function? We shouldn't assume that they have no regulation and that it's complete chaos. It may be that they do have rules, but these rules are flimsy or unsteady. In Hume's opinion, though, this isn't much better, and we can't really compare this setup with a society that has a proper government and rules of justice (just look at what goes down in Children of the Corn. Yikes!). All it tells us is that there's a need for rules in some shape or form.
Quote #8
To carry the matter farther, we may observe, that it is impossible for men so much as to murder each other without statutes, and maxims, and an idea of justice and honour. War has its laws as well as peace; and even that sportive kind of war, carried on among wrestlers, boxers, cudgel-players, gladiators, is regulated by fixed principles. Common interest and utility beget infallibly a standard of right and wrong among the parties concerned. (IV.20)
We may think that rules are overthrown when people commit crimes or in times of war, but nope. Even people like robbers have their own insider codes of conduct, and war is regulated, too. The same goes for the rules that govern sports like boxing, wrestling, and dodgeball. The point is, even when they're not laid down by the government, rules are set up wherever they're necessary and useful.
Quote #9
Inanimate objects may bear to each other all the same relations which we observe in moral agents; though the former can never be the object of love or hatred, nor are consequently susceptible of merit or iniquity. A young tree, which over-tops and destroys its parent, stands in all the same relations with Nero, when he murdered Agrippina; and if morality consisted merely in relations, would no doubt be equally criminal. (AI.17)
Remember Hume's argument that we can't study morality in the same way that we would math? He demonstrates this using an example taken from Roman history. You don't have to be a history geek to get his point, though. By comparing a tree destroying its parent to a human murdering another human, we see that that this comparison is an epic fail. Sure, it may work in principle but, on a moral level, we just don't see trees or objects in the same way that we do humans, unless you're a hardcore treehugger.