Rational utilitarianism in Herbert Spencer

This thesis aims to evaluate Herbert Spencer's philosophical thought within the framework of utilitarianism and natural law-natural rights doctrines. Spencer, who is considered one of the important thinkers of the period, tried to create a philosophical synthesis between utilitarianism and rights within the synthetic philosophy he put forward. However, a debate that arises within the political thought literature is about which of the two doctrines the thinker is ultimately closer to. This thesis argues that although the idea of natural law and natural rights is important in Spencer, the idea of utilitarianism predominates. To demonstrate this, in the first part of the study, the thinker's natural law-natural rights and utilitarian discourses are presented separately. In the second part of the study, the rationalist method in Spencer, his criticism of empirical utilitarianism and the thinker's own rational utilitarianism are discussed. In the third part, the concept of moral sense is introduced with its different meanings within the doctrine of natural law and utilitarianism, and the utilitarian, consequentialist, empirical and naturalistic qualities that Spencer attributes to this concept are explained. In the fourth part of the study, the criticism and solutions that Spencer puts forward with a classical liberal perspective and rational utilitarian reasons against new or social liberalism are discussed.