evidence it is possible to produce that something is desirable, is that people do actually desire it," it follows that intellectual pleasures (e.g., the pleasures of friendship, art, reading, and conversation) are higher and more desirable kinds of pleasures than bodily pleasures, and that a rational pursuit of one's long-term happiness requires development of one's higher faculties. In reply to the objection that there generally isn't enough time to calculate how a given act might affect the long-term general happiness, Mill sketches a kind of "two-tier" approach to ethics that accords an important place to moral rules in ethical decision-making. Mill argues that traditional moral rules such as "Keep your promises" and "Tell the truth" have been shown by long experience to promote the welfare of society. Normally we should follow such "secondary principles" without reflecting much on the consequences of our acts. As a rule, only when such second-tier principles conflict is it necessary (or wise) to appeal to the principle of utility directly. Chapter 3 In the third chapter, Mill asks what "sanctions" (that is, rewards and punishments) undergird the obligation to promote the general happiness. He explores a variety of ways in which both external and internal sanctions – that is, the incentives provided by others and the inner feelings of sympathy and conscience – encourage people to think about how their actions affect the happiness of others. The ultimate sanction, Mill claims, is internal. Humans are social animals who naturally desire "to be in unity with our fellow creatures." To prefer selfish goals over the public good runs counter to this deep-seated natural impulse. Chapter 4 In the fourth chapter Mill offers his famous quasi-proof of the greatest-happiness principle. The core of his argument is this: Everyone desires happiness. The only proof that something is desirable is that people do actually desire it. So, each person's happiness is a good to that person. Therefore, the general happiness is a good to the aggregate of all persons. Many critics have claimed that this argument relies on a dubious assumption about how individual happiness is related to the general happiness. There might be times when the general happiness can only be promoted by sacrificing the happiness of certain individuals. In such cases, is the general happiness a good to those individuals? Other critics have questioned whether it makes sense to speak of aggregates as having desires, or whether