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Emergence of Scientific Explanations of Nature in Ancient Greece

1995; Lippincott Williams & Wilkins; Volume: 92; Issue: 3 Linguagem: Inglês

10.1161/01.cir.92.3.637

1524-4539

Arnold M. Katz, Phyllis B. Katz,

Phonocardiography and Auscultation Techniques

HomeCirculationVol. 92, No. 3Emergence of Scientific Explanations of Nature in Ancient Greece Free AccessResearch ArticleDownload EPUBAboutView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessResearch ArticleDownload EPUBEmergence of Scientific Explanations of Nature in Ancient Greece The Only Scientific Discovery? Arnold M. Katz and Phyllis B. Katz Arnold M. KatzArnold M. Katz From the Cardiology Division, Department of Medicine, University of Connecticut, Farmington, Conn, and the Classics Department, Dartmouth College, Hanover NH (Visiting Lecturer) (P.B.K.). and Phyllis B. KatzPhyllis B. Katz From the Cardiology Division, Department of Medicine, University of Connecticut, Farmington, Conn, and the Classics Department, Dartmouth College, Hanover NH (Visiting Lecturer) (P.B.K.). Originally published1 Aug 1995https://doi.org/10.1161/01.CIR.92.3.637Circulation. 1995;92:637–645 At the basis of the whole modern view of the world lies the illusion that the so-called laws of nature are the explanations of natural phenomena. So people stop short at natural laws as at something unassailable, as did the ancients at God and Fate. And they both are right and wrong. But the ancients were clearer, in so far as they recognized one clear terminus, whereas the modern system makes it appear as though everything were explained. L. Wittgenstein, 19221It is generally recognized that we are living in the most productive era of science in the history of mankind. Cardiovascular science has shared in this growth, as seen in the shifting focus of research in the biological sciences from organ physiology to cell biochemistry and biophysics in the middle of this century and, over the past decade, to molecular biology.2 Yet, despite the vast body of knowledge now available, major conceptual gaps remain in our understanding of heart disease, as evidenced by surprising, and often counterintuitive, results of large-scale clinical trials designed to test what were initially believed to be logical approaches to therapy. One need only consider the recent CAST trial, which showed that drugs that suppress nonlethal arrhythmias known to herald a fatal cardiac arrhythmia increase the risk of sudden cardiac death,3 the adverse experience with inotropes for the treatment of chronic heart failure,45 and growing evidence that several classes of vasodilator drugs can worsen mortality in heart failure.67 Thus, although modern science provides valuable insights regarding the mechanisms of heart disease, it is an illusion to believe that our modern system explains everything. The present article provides an introduction for the cardiologist interested in the origins of natural science by describing the transition from mythology to science in the ancient world. Appreciation of the roots of modern science may help us to understand why, as Wittgenstein points out, the process of induction that assumes the simplest law to be correct "has no logical foundation, but only a psychological one. It is clear that there are no grounds for believing that the simplest course of events will really happen."8In 1628, William Harvey published his Exercitatio Anatomica De Motu Cordis et Sanguinis in Animalibus, which describes a tightly reasoned series of experiments designed to elucidate the circulation of the blood. This remarkable book includes a mathematical proof that the volume of blood pumped by the heart greatly exceeds the amount of food and water ingested in a day, probably the first use of mathematics to test a biological hypothesis.9 Harvey's physiology, however, is really an extension of a much older search to understand natural laws. In fact, humans have always sought to explain the natural world, and as emphasized below, the most ancient scientific explanations of our world emerged from and coexisted with an earlier mythological paradigm. The beginnings of the natural science that Harvey's creative genius advanced so dramatically can be traced to sixth century bce Greece, where, in the space of a few generations, a handful of presocratic philosophers built upon the earlier mathematics and technology of the Babylonians and Egyptians to make what may be regarded as the only true "discovery" in science: that our world can be understood not through the actions of gods and fate, but instead through natural laws whose identification could enable humans to comprehend their surroundings, and even themselves. From Mythology to Science The discovery of natural science by the early Greek philosophers did not represent a revolutionary change in our view of the world, but instead emerged through an evolutionary process in which a remarkable school of presocratic philosophers, building on the highly developed but practically oriented technology and mathematics of Babylon and Egypt, sought to understand nature by modifying an older paradigm, that of mythology. Of these early philosophers, F.M. Cornford observes: . . . there is a real continuity between the earliest rational speculation and the religious representation that lay behind it; and this is no matter of superficial analogies. . . . Religion expresses itself in poetical symbols and in terms of mythical personalities; philosophy prefers the language of dry abstraction, and speaks of substance, cause, matter, and so forth. But the outward difference only disguises an inward and substantial affinity between these two successive products of the same consciousness. The modes of thought that attain to clear definition and explicit statement in philosophy were already implicit in the unreasoned intuitions of mythology.10The transition from myth to science, therefore, represented not so much the appearance of a new rational approach to the understanding of nature as the discarding of mythical personifications of natural phenomena. The shift in perspective from mythology to science that occurred 2600 years ago in Greece was localized and limited. D.C. Lindberg says of the appearance of Greek philosophy: This was not, as some have portrayed it, the replacement of mythology by philosophy; for Greek mythology did not disappear but continued to flourish for centuries. Rather, it was the appearance of new, philosophical modes of thought alongside, or sometimes mingled with, mythology.11In fact, belief in the gods and in magic continued to be dominant in Western culture long after the Greek world had ceased to exist as a political and social entity. Hesiod The mythical origins of natural science in ancient Greece are described in Hesiod's Theogony, a poem written approximately a century before the flowering of the early presocratic philosophers. Hesiod was not a philosopher, but rather a farmer and shepherd who, according to N.O. Brown, "lived in an age innocent of philosophy. He presupposed an audience familiar with the idiom of mythical thinking, and accustomed to speculate on the great questions of life in that idiom."12 G.S. Kirk describes the Theogony as "a mass of fascinating mythologic and theological material, arranged so as to constitute a history of the world from its earliest stages down to the time when Zeus established himself as supreme god."13Hesiod begins his Theogony with an explanation as to how his world came into being: Hail, daughters of Zeus! Grant me the gift of lovely song! Sing the glories of the holy gods to whom death never comes, the gods born of Gaia and starry Ouranos, and of those whom dark Night bore, or briny Pontos fostered. Speak first of how the gods and the earth came into being and of how the rivers, the boundless sea with its raging swell, the glittering stars, and the wide sky above were created.14Of this description of "how the gods and the earth came into being," Apostolos Athanassakis argues: "Hesiod had a formidable task to perform. He had to explain the origin of the world and of the gods who rule it, and even though scientific thought as we know it did not exist in his day, his genealogical method and mythopoetic reasoning constitute a speculation that is rational in its own terms."15Hesiod describes the beginning of the world as a void or emptiness, which he called "chaos"—literally, a gap. Kirk infers that this "conception of the primordial condition as 'Chaos', a great murky gap, probably owes something to the poet's own imagination."16 Hesiod continues with an anthropomorphic description, highly sexual in its conception, that combines parthenogenetic birth and amorous, often incestuous, adventures among a race of gods whose interactions are presented in terms of conflict, often brutal and sexual. Hesiod recounts the overthrow of Ouranos—the starry Sky—by Cronos, the son born of his mating with Gaia—the Earth—and then how Cronos' son Zeus, who was also suppressed by his father, eventually overthrew Cronos and assumed leadership of the Olympian gods. Of Hesiod's view of the creation of the world, Brown observes: Proliferation is a natural law violated by Sky and Cronos when they attempt to suppress their children; they left their children no choice except to fight in order to exist, and thus involved themselves in a retributory cycle of violence. Zeus, on the other hand, proliferates constant conflict between generations, and with unparalleled Fecundity. . . . Zeus' regime thus makes a sharp break with the unnatural repression of the past and inaugurates a new order which permits natural development; it is, as the Greek philosophers say, "in accordance with nature."17Yet this "new order" is far from science. As G. Vlastos states: "The forces of nature, uncertainly personified as earth-born deities, are subdued by Zeus in the battle with Titans and brought more or less under his power. But there is no notion of natural laws issued and maintained by Zeus. So far from maintaining natural regularities, Zeus himself and the other gods over-ride them right and left."18Hesiod's Theogony, as Brown observes,19 represents the first attempt to formulate two classic problems of Greek culture: "how to find unity in diversity, and how to find a permanent principle in the midst of flux." We see later how the conflicts described by Hesiod came to be used, albeit in a very different paradigm, by the presocratic philosophers, who transformed these personifications into forces that were "wholly immanent in the order of nature and therefore absolutely law-abiding. . . ."20Possible Role of the Greek Language An important role for the fluid, yet precise, Greek language in the development of the rational philosophies of ancient Greece is suggested by Bruno Snell,21 who, like Wittgenstein,22 focuses on the role of language in providing "pictures" of the world. Snell, in commenting on the importance of assigning a mythical name to a concept or a natural force, states: "Personification as mythical Gods interprets the non-physical anthropomorphically, thus describing it as the 'embodiment of animate reality.' "23 Such an embodiment, the assigning of a quality to a mythological personage, allows a specific event or reality to be distinguished unequivocally from a concept or idea, for example, in distinguishing between a specific war and the concept of conflict. Thus, the construction of the Greek language is seen as lending itself especially well to the evolution of rational thinking. Snell postulates that the structure of the Greek language facilitated connections between myth and science: Many words which were later regarded as abstracts began their career as mythical names. In Homer, e.g., fear appears as a demon, as the Frightener, the Phobos. The extent to which these words were understood as names, even after mythic connotations had long worn off, is evident from the use of the article.24The definite article the aids the development of concepts that could then be used to formulate natural laws. For example, generalizing the experience of warmth to the hot may have been critical in the emergence of the concept that heat represents one of the four elements, or principles (see below). Thus, according to Snell, use of the definite article to define, delimit, or personify a specific concept, eg, the warm day, the frightened Trojan, could elevate these concepts to a universal status—the hot or the fear, and so make it possible to expand on these concepts—the fear is a demon, or the hot is a first principle. As Snell points out, "the generic definite article endows the substantive all at once with the qualities of an abstract, a concrete, and a proper noun."25Snell views mythical and logical thought, while similar in many aspects, as successive stages in the development of scientific thinking, but stages that are never entirely discrete. He suggests that as the Greeks developed the "seeds of logic inherent in their own speech, they laid the foundation of their own as well as all modern science."26 However, Snell's notion that mythical thought represents "the seeds of logic" is challenged by some modern scholars, whose opinions are well summarized by G.E.R. Lloyd's remark: "The notion that there is or was a mythological or pre-rational or pre-logical mentality is at best grossly oversimplified and at worst a piece of dangerously misleading propaganda."27 Similarly, B. Williams challenges Snell's view that the Greeks of Homer's time lacked the capacity to make decisions based on thoughtful analyses of their world.28 We agree, but we believe that Snell is correct in his contention that the Greek language helped the presocratic philosophers to lay the foundation of their own and of modern science. We note, however, Wittgenstein's reservation: "The primitive forms of our language: noun, adjective, verb, show the simple picture into whose form language tries to force everything,"29 which is true even today, where imprecisions in the pictures generated by our use of language contribute to the problems that still face those who seek to understand how to treat patients with heart disease. One wonders, for example, whether widespread use of the terms "heart attack" and "myocardial infarction," by obscuring the fact that these conditions are due to blood vessel disease in which the heart is the victim and not the perpetrator, delayed clinical trials of the thrombolytic agents now known to restore coronary flow and improve survival in patients with acute myocardial infarction. Depersonification in the Transition From Myth to Science We have already indicated that replacement of mythological cosmogonies, such as described by Hesiod, with the science of the Greek philosophers did not represent a radical shift in focus; in fact, the goals of myth and of science are similar. As Snell notes, Hesiod's Theogony attempts to "bring order into the phenomena of the world by including all gods and demons in a genealogical system,"30 much as modern science pursues the same goal through discovery and systematization of natural laws. The objective is similar: to achieve order and understanding; only the approach differs. The transition from the mythological paradigm exemplified by Hesiod, who attempts to make sense of natural phenomena by personifying them as gods, and the scientific paradigm of the later Greek philosophers, who address natural phenomena in rational and scientific terms, is illustrated by the endowment of many gods of Greek mythology with properties similar to those described later in the language of science and logic. As stated by Vlastos: "What is there more typical of Greek religion than the personification of winds, springs, rivers, earth, seasons, graces, love, victory, justice, peace etc."31 Dike, the daughter of Zeus and Themis who personifies the concept of justice, is described by Hesiod as reporting to Zeus to "[denounce] the designs of men who are not just."32 Three hundred years later, the transition is completed in Plato's Republic, in which justice becomes an absolute and abstract ideal. Yet Hesiod's anthropomorphic description of justice as a virgin daughter of Zeus can be recognized as an antecedent of Plato's discourse on justice as a philosophical concept. Narrowing of the distance between gods and humans in Greek mythology was facilitated by the fact that even for the Greeks of the eighth century bce, the gods were not remote and incomprehensible. Homer, a contemporary of Hesiod, richly endows the gods in his epic poems with human characteristics and foibles. As Richmond Lattimore points out: "The gods of Homer are mainly immortal men and women, incomparably more powerful than mortals, but like mortals susceptible to all human emotions and appetites, therefore capable of being flattered, enraged, seduced, chastized."33 This "god-apparatus," as Eric Havelock calls it, is more than an anthropomorphic system of belief. It represents a tool used by the oral poet composing his song in a preliterate world in which "the play of divine habit and behavior had to function in place of causal accounts of relationships between forces and materials. Since there are no men extended through the environment to provide the behavior, the consciousness demands that supermen be put there to supply the need."34 Yet assignment of recognizable human qualities to the Greek gods appears to have been an antecedent to the depersonification of natural forces that evolved during the sixth century bce in the Ionian seaport of Miletus (Fig 1).Miletus The emergence of Greek science is commonly traced to Miletus, a Greek colony on the Mediterranean coast of what is now Turkey (Fig 2). According to Kirk and Raven: It was in Ionia that the first completely rationalistic attempts to describe the nature of the world took place. There, material prosperity and special opportunities for contact with other cultures—with Sardis, for example, by land, and with the Pontus and Egypt by sea—were allied, for a time at least, with a strong cultural and literary tradition dating from the age of Homer. Within the space of a century Miletus produced Thales, Anaximander, and Anaximenes, each dominated by the assumption of a single primary material, the isolation of which was the most important step in any systematic account of reality. This attitude was clearly a development of the genetic or genealogical approach to nature exemplified by the Hesiodic Theogony. . . .35Kirk and Raven here allude to the geographical position of Miletus, situated across the Aegean Sea from Attica and the Peloponnesus, which was a crossroads, both geographical and intellectual, linking the then-emerging Greek mentality with the older civilizations of Asia Minor and Africa, notably Babylonia, Assyria, and Egypt. Lindberg postulates: Ionia may, like many frontier societies, have encouraged hard work and self sufficiency; in return, it offered prosperity and opportunity. It also brought Greeks into contact with the art, religion, and learning of the Near East, with which Ionia had cultural, commercial, diplomatic and military contact.36Benjamin Farrington refers to Miletus as "the most go-ahead town in the Greek world," whose active trade with Mesopotamia by land and Egypt by sea was carried out by practical men "whose philosophy consisted in the fact that, when they turned their minds to wondering how things worked, they did so in the light of everyday experience. . . ."37In assessing the influence of the Near East on the Greeks, Lloyd describes the "debt" of Greek astronomy to the Babylonians as providing "the material on which to construct theories, not in the theories themselves or in the idea of the possibilities of such theories."38 He suggests that the unique element was that in astronomy, mathematics and medicine the Greeks preeminently bring into the open and discuss second-order questions concerning the nature of the inquiry itself. Much as the Egyptians and Babylonians contributed to the content of these studies, the investigations only acquire self-conscious methodologies for the first time with the Greeks.39Vlastos goes further in stating that "they [the presocratic philosophers] and they alone, not only among the Greeks, but among all the people of the Mediterranean World, Semitic or Indo-European, dared transpose the name and function of divinity into a realm conceived as a rigorously natural order and, therefore, completely purged of miracle and magic."40 But as pointed out by Wittgenstein,1 while freed of reliance on God and Fate, modern science only gives the appearance that everything is explained; hence the not-infrequent surprises when therapies predicated on logical theories of disease are subjected to clinical trial.34567Lloyd, commenting on the intellectual climate of sixth century bce Miletus, points out that the Greek city-state "created an audience of people who had extensive experience of evaluating evidence and arguments in the context of legal and political debates, and it is that audience that is crucial to the development of the particular styles of reasoning characteristic of early Greek speculative thought."41 He notes that Miletus provided a unique setting for the "rise of theoretical inquiry" because of its economic and cultural advantages as well as its political circumstances: Thanks to its alliances first with Croesus and then with Cyrus, [Miletus] retained more political independence during the greater part of the sixth century than most of its Greek neighbors. Internally it was far from enjoying a settled constitution. Herodotus (5.28) refers to the party strife it suffered, and it was ruled intermittently by tyrants. But these upheavals did not prevent, and may even have done a good deal to encourage, the development of political institutions and political awareness. The growth of a new critical spirit in philosophy in the sixth and fifth centuries may be seen as a counterpart and offshoot of the habit of free debate and discussion of politics and law throughout the Greek world.42The Milesian Philosophers The economic, geographic, cultural (Fig 3), and political conditions in ancient Miletus stimulated three presocratic philosophers to make the monumental transition from mythological to scientific explanations of the natural world. Although available evidence is limited, enough is known of the writings of Thales, Anaximander, and Anaximenes—the three Milesian philosophers—to suggest that they viewed the world using a rational, and often surprisingly modern, cosmogony. Lloyd points out that most of what we know of the three Milesians comes from Aristotle and Theophrastus, the "doxographers," who certainly had their own agenda in selecting the passages they cited from these philosophers. Yet Lloyd concedes that one of the notable products of classical antiquity lies not so much in the actual natural scientific theories proposed, as in the competing theories of nature and of natural science themselves. It would be an exaggeration to say that the sole Greek contribution to science lies in the philosophy of science, but it can be argued that was one of their more durable contributions.43We would go further, in agreement with J. Longrigg, who writes that the Milesian philosophers were the first to attempt "to explain the world in terms of its visible constituents without recourse to supernatural intervention . . . ,"44 and Vlastos, who, describing the contribution of the presocratic philosophers, affirms: "Doubtless their concept of nature as a self-enclosed, self-regulative system is the intellectual foundation of science, and they who built it out of incredibly inadequate materials have every right to be considered pioneers of the scientific spirit."45 L. Wolpert agrees: Never before had someone put forward general ideas about the nature of the world that might be universal, ideas that tried to explain the nature of the world in a way quite unlike the explanations provided by all-pervasive myths. For the first time there was a conviction that there were laws controlling nature, and that these laws were discoverable. . . . This was one of the most exciting and important ideas in the entire history of mankind.46Among the most interesting aspects of the early Greek philosophers is that we know who they were. As noted by Wolpert: The stage for science had been set, and for the first time there were named actors, with strong views and personalities. This was a radical departure, for Egyptian and Babylonian medicine, mathematics and astrology can, apparently, be combed in vain for examples of a text where an individual author explicitly distances himself from and criticizes the received tradition in order to claim originality for himself; whereas in Greece this became normal procedure.47The Milesian philosophers, in our view, made the overarching discovery of Western science: that the world is governed by natural laws that can be studied without referring to theistic (deistic) allegory to explain what we do not know. Yet, as has already been pointed out, evidence that this science is imperfect is seen in clinical trials that have uncovered serious errors in our understanding of the natural laws initially believed to operate in heart disease. Whether these errors reflect imperfections in our ability to apply these laws to cardiac patients, or whether instead they reflect the illusory nature of these laws, is a question that is beyond the scope of this article. Thales The first of the Milesian philosophers was Thales, who lived from approximately 624 to 548 bce. He is thought to be an engineer with a working knowledge of the advanced Near Eastern technology that had reached Ionia in the sixth century bce. Thales probably learned much from the Egyptians, whose skills are called by Kirk and Raven "the traditional fountain-head of Greek science"48 and whose contribution to Greek thought has recently been highlighted by Martin Bernal.49 The Babylonians and Egyptians were expert builders; as Wolpert points out, the former had tables listing the sides of right-angled triangles and may even have been aware of the Pythagorean theorem.50 Thales' contribution, however, is more than the application of the engineering skills of the ancient Near Eastern world; for example, he is said to have developed several general theorems that underlay the transition of geometry from a tool of technology to a science. This distinction is important. Wolpert defines technology as the crafting of a usable object, whereas the product of science is an idea,51 so that Thales' abstraction of geometrical theorems from their practical use in ancient technology would have been a major advance in the development of the science of mathematics. Lloyd writes: . . . what was lacking, from both Egyptian and Babylonian geometry, so far as we can tell, was the notion of geometrical proof. . . . There appears to be a fundamental distinction between the general aims of Egyptian and Babylonian geometry on the one hand, and of Greek geometry on the other, in the concentration, in the latter, on demonstration.52Thales' abstraction of natural laws from observations of his world played a similar role in the emergence of science. Modern writers often state, taking as a basis Aristotle's Physics, that for Thales, the primary substance from which the earth was constituted was water: Thales, the founder of this type of philosophy, says the principle is water (for which reason he declared that the earth rests on water), getting the notion perhaps from seeing that the nutriments of all things is moist, and that heat itself is generated from the moist and kept alive by it.53Thales' view of the primacy of water, however, is by no means novel or a radical departure from earlier mythological cosmogonies. A similar view is found in a number of Near Eastern cultures (Egyptian, Babylonian, and even biblical) to which Thales had access, and a reference to the primacy of water is found in the Iliad of Homer: And the voice of Sleep the soft and soothing drifted back . . . "Hera, Hera queen of the gods and daughter of mighty Cronos— any other immortal god who lives forever, believe me, I would put to sleep in a wink, even the rolling tides of the great Ocean River the fountainhead that brought them all to birth."54For Homer, of course, the idea of water as the "fountainhead" of the gods is based not on a scientific paradigm but rather on one of mythology, another example of Havelock's "god apparatus." In describing these beginnings, Lloyd recognizes the nature of the transition from myth to science when he insists: . . .one thing does seem clear if we are to say anything about Thales' cosmogony at all, and that is that he was not simply imitating any myth, whether Greek or non-Greek. At the very most he was selecting and critically evaluating mythical ideas, and Aristotle at least would represent him (conjecturally) as having been influenced by naturalistic considerations above all.55Thales' debt to the Greek language in his shift from anthropomorphic myth to science is pointed out by Snell: With this [explanation] he [Thales] follows up a suggestion of Homer who had declared that Ocean is the origin of the gods. Only Thales used a concrete noun in the place of a mythical name. Once before, by Hesiod, an attempt had been made to bring order into the phenomena of the world by including all gods and demons in a genealogical system. But even that attempt to see the world as a systematically arranged pattern had been confined to the use of mythical names. Now Thales transcends beyond the pace of individual things by postulating a common substance to them all. These references to a substance, so very important in early thought, continue to exert their influence in all subsequent speculations of Greek natural philosophy.56Thales' famous prediction of the solar eclipse on May 28, 585 bce, is described by Herodotus: another combat took place in the sixth year [of a war between Io