out of the legal code, and extending this right from cases of direct oppression to cases of interbranch constitutional encroachment in "mix'd governments", adding two "philosophical reflections": first, Parliament's authority to exclude the heirs of rulers they have deposed, but not the heirs of rulers who simply died, derives from mere imaginative inertia; second, a contested change in authority may acquire legitimacy retroactively from a stable line of successors. Hume then examines international law: the similarities between individuals and entire nations yield the same three laws of nature as before, but the special needs of nations call for special rules (e.g., diplomatic immunity). But because cooperation among nations is "not so necessary nor advantageous as that among individuals", moral rules have significantly less force in international contexts and "may lawfully be transgress'd from a more trivial motive"—i.e., a weaker natural obligation brings a weaker moral obligation. Only general practice can determine exactly how much weaker the obligation is, and indeed the fact that the rules are recognised to be weaker in practice shows that people have "an implicit notion" of their artificiality. The final section examines the social rules governing the sexual behavior of women ("chastity and modesty"), which Hume takes to nicely illustrate how artificial virtues grounded only in social interest can nevertheless acquire universal force. It is boringly obvious that these rules are not exactly natural, and yet they solve a natural problem: a child needs both parents, parents need to know the child is theirs, and paternity is subject to uncertainty. And since questions of sexual fidelity cannot be settled in courtrooms, society needs informal norms (with weakened evidential standards and heightened reputational import) policing fidelity in women. Indeed, Hume adds, given female weakness in the face of sexual temptation, society needs women to feel a strong aversion to anything even suggestive of infidelity. This solution might sound unrealistic in the abstract, but nature has made it a reality: those personally concerned with infidelity have swept along the unconcerned in their disapproval, molded the minds of girls, and extended the general rule into apparently irrational territory, with "debauch'd" men shocked at any female transgression and postmenopausal women condemned for perfectly harmless promiscuity. Men instead stake their reputation on courage (a partly natural virtue) and enjoy looser sexual norms, fidelity in males (like cooperation among nations) being less important for society. Part 3: Of the other virtues and