Utilitarianism is a book released in 1863 by John Stuart Mill to provide the support for the value of utilitarianism as a moral theory and to respond to misconceptions about it.
The book consists of five chapters; the introduction to the essay, the definition of utilitarianism and its common criticisms, the rewards it can offer the methods of proving its validity and in the final chapter looks at the connection between justice and utility and argues that happiness is the foundation of justice.
Mill delves into how 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 arguing that humans are social animals who naturally desire to be in unity with their fellow creatures. That happiness is the only thing that humans find valuable without any external validation.
In the essay he also responds to a number of criticisms of utilitarianism such as; it is a doctrine worthy only of swine, it's too demanding, it fails to recognize that happiness is unobtainable, makes people cold and unsympathetic, it is a godless ethics and fails to recognize that in making ethical decisions there usually isn't time to calculate future consequences.