It is a well-organized, logical argument, written with engaging style. The basic idea is that to live not to live well, but to live at all one needs to interact with the world in certain ways and use one s faculties to contribute to the preservation and enhancement of one s life. Beginning with that premise makes the theory an example of what philosophers call ethical naturalism, but it is a naturalism that is not unchosen and externally imposed. Morality, on this view, is chosen, but natural in the sense of referring to the way the world works. Since the fact of human life is objective, values are objective.
Rationality is our objective tool for discovering and then choosing the right values.
With this approach, Smith distances herself from the fashionable subjectivism and cultural relativism that pass for ethics these days. Since rationality is one of the powers at my disposal, I ought to use it to preserve and enhance my life. Pretending that things are other than they are . . . Smith is arguing that life is what makes values possible, but also what makes them necessary. In addition to criticizing the intuitionist, contractarian, and rationalist approaches to ethics, Smith distinguishes her ethical egoism from hedonism and subjectivism.