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

Galen insists that genuine epistêmê, in the Aristotelian sense of securely-founded scientific understanding, is available to the serious medical investigator. The foundations consist in propositions that are evidently true, and hence require no further support. These come in two types: those evident to the senses and those evident to reason, and these are ex heautôn pista, self-crediting, intrinsically trustworthy. On the basis of such propositions the diligent inquirer can erect a firmly-founded structure of practical knowledge, a technê, but one which is, none the less, in a genuine sense demonstration. In this chapter I re-examine what Galen says about a number of inter-related key issues: What is the ‘orderly method’ of discovery which Galen regularly commends, and berates his opponents for failing to adhere to? What supplies the ‘context of justification’ for such a firmly-founded science, and how does this relate to Galen’s oft-repeated affirmation of the necessity for empirical testing, peira? And finally, and relatedly, what specific role in all of this is played by what he calls ‘differentiated experience’, peira diorismenê?

This chapter does not directly address the issue of the relations between biology and cosmology as such, although it refers in passing to Galen’s deployment of the microcosm/macroscosm model for the understanding of the nature of the human form and its relation to, indeed its mirroring of, the overall structure of the universe. But it does deal with how and why Galen thought that a proper understanding of the enormous complexity, goal-directedness, economy of animal and pre-eminently human structures demands explanation in terms of a providential, artistic and indeed aesthetically motived designer-god. That is, a proper understanding of the biosphere, and in particular of human physiology, demands a commitment to, and an understanding of, what Galen takes to be a fundamental cosmological fact, namely that the universe is indeed providentially ordered. The bulk of this chapter is devoted to teasing out in detail the nature and working-out of these fundamental commitments.

PRELIMINARIES

Some time early in the first century, Philo and Antiochus, the two leading philosophers of the Athenian Academy, had a serious philosophical falling out. Philo advocated an externalist epistemology, holding that it was reasonable to suppose that things could be known, even though they could not, individually, be known to be known; Antiochus responded that the only way one could know that one knew anything was by knowing of some particular thing that one knew it; and thus (according to Cicero: Acad. 2.44, 111) strayed perilously close to Stoic dogmatism. Neither option appealed to their colleague Aenesidemus:

Our knowledge of Aenesidemus is sadly restricted. For his views, we are indebted principally to a précis of his Pyrrhonian Discourses from Photius of Byzantium’s library catalogue (from which 1 above is excerpted). As for direct references, Sextus refers to him by name some fifteen times (but some of these are problematic: see below, section IV), Diogenes a few times more; and that’s about it.

INTRODUCTION

Galen was no sceptic. On several occasions he refers derisively to ‘boorish Pyrrhonists’, suggesting that scepticism, at least in its more extreme forms, is a matter of a lack of culture, an intellectual infantile disorder. Time and again, he stresses that, if only the inquirer is blessed with diligence, honesty and intelligence, and armed with the proper logical tools of rational discourse, he can aspire to a genuine understanding of the way in which the physical (or more particularly the physiological) world works. In Elements According to Hippocrates (Hipp.Elem.), he argues that the successful medical practitioner needs to know the fundamental elements that make up physical objects, and how they interrelate to one another (although as we shall see, there are some qualifications to this necessity); he affirms that it is demonstrable that monism is false; and even more strikingly affirms that Hippocrates himself (in Nature of Man) demonstrated its falsity (Hipp.Elem. I.415–16; cf. 416–42). In a similar vein, On Mixtures (Temp.) talks of the importance of understanding the real states of affairs in regard to the internal mixtures of the body and its various properties, phenomenal and causal, and of properly assessing the varying degrees of heat, cold, dryness and moisture of the various parts. Another ‘physical’ treatise, On the Natural Faculties (Nat.Fac.), argues for the reality of certain fundamental natural capacities (attraction, retention, alteration and expulsion) possessed by distinct parts of animals' bodies in virtue of which they can perform their functions, and against what he stigmatises as the excessively crude materialism of the atomists and their various anti-teleological acolytes.