Abstract

This thesis aims to discuss Thomas Reid’s (1710-1796) theory of the first principles of knowledge, more particularly, the first principles of philosophy of mind, morals and politics. In the first chapter, I discuss Reid’s foundationalist commitments in philosophy of mind, morals and politics. I argue that he is clearly a foundationalist about speculative and moral knowledge, but it is not clear if he keeps foundationalist commitments with regard to political knowledge – the first principles of politics are not self-evident beliefs: they are not justified from the start and, therefore, they do not have what is needed for being basic beliefs in a foundationalist view of the structure of knowledge. In the second chapter, I discuss Reid’s understanding of the sources of speculative, moral and political knowledge, namely, common sense and knowledge of mankind. I argue that while philosophy of mind and morals are based upon the first principles of common sense – immediate and irresistible beliefs due to the original constitution of mind, politics is based upon first principles of the knowledge of mankind – beliefs that are due to a mixture of the sagacity and the experience of the political scientist who lives among other human beings in a political society. In the third chapter, I try to explain Reid’s comprehension on the first principles of philosophy of mind, morals and politics. I try to explain what a first principle of knowledge is, how to understand the distinction between the principles of contingent and necessary truths and what the means we have to identify the first principles of knowledge are. The fourth and last chapter is entirely dedicated to common sense. More particularly, I discuss how Reid defends the first principles of common sense from the skeptical attack.