Russ Shafer-Landau's Theory Of Utilitarianism

In the Ethical Life, Russ Shafer-Landau talks about John Stuart Mill and his theory on Utilitarianism. Mill states that Utilitarianism is the most influential presentation of doctrine and agrees with the Utilitarian belief of which is ethical decisions should be based on the greatest happiness for the greatest number of people. But if this is true, then would people not act out of personal interest?
Utilitarianism, as previously stated, is the belief of which ethical decisions should be based on the greatest happiness for the greatest number of people. Like any other form of consequentialism, the theory believes that whether actions are morally right or wrong depends on their effects. When it comes to elements that calculate the greatest amount of happiness, many would consider: Pleasure minus pain, intensity, duration, fruitfulness, and likelihood when deciding what one should do. In addition to the five elements, John Stuart Mill believed that Act Utilitarianism is for the greater good. For example: If more of your friends want to go play volleyball rather than basketball. What decision do you make? Typically, you would pick volleyball because it would make the most people happy. In which, shows that people do sacrifice things they want for the greater
An example of this would be that whenever people want to buy something for themselves or their family, they must first determine whether they could create more well-being by donating their money to help unknown strangers who are seriously ill or impoverished. If more good can be done by helping strangers than by purchasing things for oneself or people one personally cares about, then act utilitarianism requires us to use the money to help strangers in need. Why? Because Act Utilitarianism requires impartiality and the equal consideration of all people’s needs and