Essays 8 and 9 are unique within the context of Proclus’ Republic Commentary in being so obviously different treatments of more or less the same subject matter. Accordingly, we will provide one introductory chapter for both essays.

The chapter aims at investigating the way Galen constructs his philosophical theories in dialogue with his predecessors, both by adhering and by opposing to their doctrines. For this purpose, it focuses on a certain part of his epistemology, namely his account of sense perception and, in particular, his theory of vision. I argue that Galen’s perceptual theory starts from material he finds in the Platonic dialogues, but revises it significantly either in order to reply to objections raised by Plato’s opponents or in order to rebut unfortunate, at least to his mind, adaptations of the Platonic inheritance. Indeed, in his attempt to defend Plato’s views on sense perception, Galen does not recoil from borrowing whatever seems to him valuable from rival philosophical schools, and it is this enriched reworking of the Platonic theory that he adopts as his own philosophical stance. To fully reconstruct and comprehend Galen’s method in his general theory of sense perception and in his theory of vision, I draw my evidence from what Galen tells us about these topics in his extant works, and especially in the seventh book of his treatise On the Doctrines of Hippocrates and Plato.

This chapter discusses a number of passages from Galen’s work that illustrate his idea of dialectic as a tool for scientific reasoning and discovery in particular. Through logical methods such as division the researcher identifies observable properties of the thing under examination (e.g. the heart, or brain) that indicate its hidden cause or essence, i.e. function (e.g. being the centre of a particular psychic faculty) in the context of theory formation. The medical practitioner for his part will profit from dialectical method when it comes to establishing a diagnosis. The notion of indication or sign is pivotal in that its bridges the stage of discovery and that of confirmation through demonstrative proof. In addition, ‘dialectical’ serves as a label for plausible assumptions and arguments in cases where truth is unattainable or at any rate has not yet been established through demonstrative proof. Various influences are involved in Galen’s version of dialectic: Plato’s Phaedrus and Timaeus, Academic epistemology, Aristotle’s works on scientific method as well as input from the medical schools, most notably Rationalist ideas (e.g. indication). His resulting position can best be described as an original synthesis developed with a view to the interests of the medical theorist and practitioner.

They say that the bee is sacred to the Muses, a teacher for human beings concerning the royal and political life. Therefore, if it pleases you to give the name ‘the bee’ to the summary of the opinions of the ancients concerning the speech of the Muses by Plato 17 and of the exposition of it that I am furnishing, the Muses will not blame you for using that name nor will Plato, the mouthpiece of the Muses as I think, who is treating the change of constitutions in this speech that he dedicated to the Muses.

He seems to me to be responding to those who lay claim to political knowledge that the change of constitutions from the higher to the next lowest does not come about by necessity.

Overview of the main issues in Galen's scientific epistemology , the state of the art, and the contents of this volume.

There are three arguments in the ninth book of the Republic showing the happiness (eudaimonia) of the most just life and the wretchedness of the unjust. The first is made by analogy of ways of life with constitutions, the second from the means of judging, by which [types of individual] are judged more or less than one another,8 the third on the basis of the perfection in their activities, whether it is unmixed in any way with the opposite, or whether it is mixed. Since for some people the goal (telos) is pleasure, but for others it is intelligence (phronêsis), if it should be shown that the just man is superior in each individually and in both together, he would with good reason win the prize for victory, even if [his goodness] should escape the notice of both gods and human beings. This then was the challenge lying before Socrates.

When Socrates has established as rulers of the best political order those who are legitimately lovers of learning and who are not counterfeit philosophers, and when he has declared them worthy to be spectators of the universals – and the affairs which are governed by them will come to resemble those universals – he postulates that most of all they will understand this very last object of learning. Since his companions have asked for a discussion from him as to what this means, and what the final one of all the objects of learning hints at,18 he says that they have already heard this many times before, namely that this is the Good, which all things desire. And it is not possible to say where one should turn one’s thinking (dianoia),19 if one should neglect this axiom. He announces that he will show what exactly the good is.

Despite the title of Essay 12 (‘On the Cave in the Seventh Book of the Republic’), the text which survives deals not only, and in fact not primarily, with the famous image of the Cave, but also with the image which precedes it in the Republic, the Divided Line. Due to a lacuna in our essay, of uncertain length but of at least one entire folio, a large part of Proclus’ discussion of the Cave is lost to us. Proportionately, therefore, we have more remaining to us of the discussion of the Divided Line. By the nature of the passages which Proclus analyses here, there is some overlap with Essay 11 (in relation to the Good), and Essay 10 (in relation to the ascent through the distinct ontological levels).

The chapter focuses on the central role Galen ascribes to his own first-person ethical and emotional experience in the construction and defense of his ethical theory and therapy of the emotions. I argue that by appreciating the complex role that Galen’s autobiographical episodes play in his moral works, we can better understand both the theory he proposes and his conception of the role that first-person experience and philosophical argument play in moral education and judgment. As I show, Galen’s emphasis on his own first-person ethical experience not only fits well with his more general epistemological view of the importance of experience in the acquisition of scientific knowledge, but also makes a substantive contribution to his account of moral education and emotional therapy.

The Tenth Book is divided into three principal topics. The first of these is directed towards a critique of poetry on the grounds that it is mimetic, but not educative of souls. The second establishes the immortality of the soul and reveals its kinship with the divine. The third provides the myth itself, which exhibits providence as a whole, both daemonic and divine, which governs souls both descending into becoming and transcending becoming, and the multi-form ways of each. These being the three subjects, it is clear that the first proposes to separate us from material images (eidôlon) and to lead us up from the illusions (phantasia) of false learning, because these draw us down to the very last of existent things, which are in fact partial (merikos) and imitative of existent things, but do not truly exist themselves, and [to lead us up] from what is simply and entirely a fictive life.

The chapter focuses on the methodological debate between Empiricist and Rationalist schools of medicine, as portrayed in Galen’s early treatise On Medical Experience (Med.Exp.). This dense and philosophically-sophisticated text, preserved for the most part only in an Arabic translation, supposedly presents the substance of a dispute, witnessed by the young Galen, between his Rationalist teacher Pelops and an Empiricist opponent, about the respective roles of experience and reason in medicine. Analysing the arguments on both sides, in particular as they concern the question of inductive generalisation and the nature and validity of the empirical procedure known as epilogimos, the chapter shows how Galen’s presentation of a sequence of responses and counter-responses between the two protagonists serves to prefigure his own complex and hugely influential synthesis of the empirical and rationalist procedures in his own mature methodology.

This chapter examines the change in the fortunes of Galen that began to occur at the time when Aristotle was beginning to be recognised as the supreme ancient authority in the Arabic world, eventually eclipsing the reputation of Galen, at least as a philosopher. It shows how Galen’s pre-eminence as a philosophical authority was gradually undermined by a sequence of commentators on his great work of scientific method, On Demonstration. Its main focus is on al-Rāzī’s Doubts about Galen composed in order to bolster Galen’s reputation when it was beginning to be challenged, notably by al-Fārābī. Central to al-Rāzī’s (partial) defence is an endorsement of Galen’s strong, Aristotelian notion of a demonstrative empirical science, as well as of his rejection of mere induction and argument from example as appropriate means of arriving at the requisite axiomatic principles. However, al-Rāzī takes Galen to task for failing to observe his own distinctions, and for taking insufficient care to ground his own fundamental assumptions. Al-Rāzī then applies his modified Galenian method to theological arguments, notably design-arguments, and in order to reject supposedly fallacious materialists’ arguments against creation. The article then turns to al-Fārābī, who in contrast directly attacks Galen’s inferential methods to support contrary, Aristotelian, positions.