Original and penetrating, this book investigates of the notion of inference from signs, which played a central role in ancient philosophical and scientific method. It examines an important chapter in ancient epistemology: the debates about the nature of evidence and of the inferences based on it--or signs and sign-inferences as they were called in antiquity. As the first comprehensive treatment of this topic, it fills an important gap in the histories of science and philosophy.

Truth, etc. is a wide-ranging study of ancient logic based upon the John Locke lectures given by the eminent philosopher Jonathan Barnes in Oxford. The book presupposes no knowledge of logic and no skill in ancient languages: all ancient texts are cited in English translation; and logical symbols and logical jargon are avoided so far as possible. Anyone interested in ancient philosophy, or in logic and its history, will find much to learn and enjoy here.

‘Aristotelian logic’, as it was taught from late antiquity onwards and as it can be found in logic compendia up until the 20th century,2 commonly included a short presentation of the argument forms modus (ponendo) ponens, modus (tollendo) tollens, modus ponendo tollens, and modus tollendo ponens: (For brevity, I shall call arguments of these four types ‘modus ponens type arguments’.).

Aristotle was the first thinker to devise a logical system. He drew upon the emphasis on universal definition found in Socrates, the use of reductio ad absurdum in Zeno of Elea, claims about propositional structure and negation in Parmenides and Plato, and the body of argumentative techniques found in legal reasoning and geometrical proof. Yet the theory presented in Aristotle’s five treatises known as the Organon—the Categories, the De interpretatione, the Prior Analytics, the Posterior Analytics, and the Sophistical Refutations—goes far (...) beyond any of these. (shrink)

In this paper, Plotinus' treatise On Dialectic I.3 [20] is discussed. In the first part of the paper, I argue that for Plotinus the importance of dialectic stands in the method of division that enables one to grasp the ‘what it is’. I present and examine some passages which contain a description of dialectic and an account of its activity. I then look into the reasons why Plotinus affirms the superiority of dialectic, as he conceived it, over logic, as the (...) Peripatetics and the Stoics conceived it. The second part of the paper explores the relation between dialectic and truth and that between dialectic and soul: in this discussion Plotinus offers some interesting and more original epistemological remarks. (shrink)

Modern interpreters have often regarded Aristotle’s Posterior Analytics as a mystery, or even a bit of an embarrassment. In his treatises on natural science and ethics, Aristotle is constantly concerned to review the opinions of his predecessors and of people in general; where appropriate, he also takes note of experiential observations, some of them highly specialized. However, the traditional view of the Posterior Analytics is that it advances an almost Cartesian picture of sciences as deductive systems founded on intuitively evident (...) first premises. How are these to be reconciled? (shrink)