In raising these questions, and suggesting some answer, political philosophers are not (or needn't be) appealing to any esoteric
form of knowledge. they are inviting their readers to reflect on their own political values, and to see which ones they care about most in the final analysis. Along the way they may add in some new pieces of information. For instance,when contemplating the
value of economic growth, it is relevant to see how people whose material living standards are very different score in terms of physical indicators such as health and mortality, and psychological indicators such as how satisfied they feel with their lives. Political philosophers therefore need to have a good grasp of social and political science.