Greek Science

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The activities characterized as Greek science cover a wide range of practices and theories that do not correspond to modern science in a simple or meaningful way. The boundaries between disciplines were fluid in the ancient period and the definition of subjects and methodologies were discussed vigorously. Hence, it is often futile to try to draw firm boundaries between subjects such as philosophy, medical theory, mathematics, technology, astrology, and astronomy. Rival theories were discussed and challenged to produce a wide range of competing theories and methodologies. Indeed, an important characteristic of much Greek scientific thought is that it is self reflexive and often concerned with "second order" problems such as what constitutes a good theory or a persuasive proof.

Early Cosmology

Thales, Anaximander, and Anaximenes (sixth century b.c.e.)all from Miletusare often identified as the earliest Greek philosophers and cosmologists. This identification is partly due to Aristotle (384322 b.c.e.), who presented them as "fore-runners" for his own physical theories. Aristotle is also the main source for their work, so his accounts must be treated with care as they are frequently colored by his theories. More generally, because so little is known about them, the Milesians have proved a malleable material to later thinkers in search of a Greek origin for their discipline.

The Milesians dealt both with natural phenomena, such as earthquakes and lightning, and with the structure of the cosmos, for instance how the earth is supported. Their explanations refer to the physical properties of things, but often rely on reasoning rather than observation. Thales supposedly argued that the earth is supported by water, while Anaximander stated that the earth rests in the middle of the cosmos, because it has no more reason to go in one direction than another. Aristotle identified a fundamental physical entity in each of the thinkers' theories: water, the boundless, and air, respectively. It is unlikely, however, that all the Milesians used these entities as material building blocks of the cosmos in the way that Aristotle envisaged.

The theories of the Milesians are often contrasted with mythological accounts found in Hesiod and Homer. However, while the Milesians do not refer to actions of the gods in their cosmologies, their theories owe much to earlier Greek and near-Eastern myths and their explanations are speculative.

The Milesians were followed by an array of thinkers criticizing and developing their thoughts. Among these were the Atomists, who argued for an infinte cosmos consisting of atoms and the void, and governed only by material interaction.


Plato's (427347 b.c.e.) main interest was with morals and he distanced himself from the material forms of explanation found in the Milesians and the Atomists. In the Timaeus he gives an account of the cosmos based on theology, in which the world is created by a divine craftsman. With this image he clearly demonstrates his commitment to design and an ordered and purposeful universe.

According to the account in the Timaeus, the Earth lies at the center of the cosmos and consists of atomic elements shaped like regular solids; geometry is thus built into the system at the most basic level. The cosmos has a soul and is itself a living being. After the creation a little soul was left over and human souls consist of remnants of the world soul. Studying the geometrical regularities exhibited by the movements of the stars and planets improves the human soul, because they mirror the world soul. According to Plato, astronomy should not be studied for its usefulness or in order to understand the physical world. Rather Plato recommends in the Republic that astronomy is studied to direct the mind toward an unchanging reality of which the sensible world is but a faint image.

Because of Plato's lack of interest in the sensible world he has often been seen as an enemy of science. However, this view must be tempered not least because of his emphasis on the fundamental role of mathematics. Plato also founded the Academy, which drew many eminent mathematicians and philosophers, among them Plato's most famous student, Aristotle.


The works of Aristotle are of special interest in the history of science, not just because of his physical theories and their immense influence, but also because of his profound interest in how we should organize and understand our knowledge of nature. In Posterior Analytics, Aristotle offers the first technical definition of knowledge, episteme, as an organized body of deductive arguments. Although Aristotle did not himself adhere to his own rigirous requirements for presenting knowledge, the idea of establishing strict conditions for what counts as knowledge and for its presentation was highly influential.

Aristotle's Physics sets out a program for how to study nature. He argued that to know about a thing or a phenomenon one has to consider its four causes: first the material cause, which asks what something is made of; second the formal cause, which concerns its shape or organization; third the efficient cause, which is the agent or "origin of change" that produced the thing; and last the final cause, which is the "end" or purpose of something. For Aristotle nature is directed toward the best. The teleology in Aristotle's approach to nature is particularly evident in his thoroughly researched biological treatises where functional explanations play an important role.

In Aristotle's account of the cosmos, all matter on earth consists of combinations of four elements: earth, water, fire, and air. Each of the elements has a natural direction of motion: downward for the former two, and upward for the latter. Thus the Earth is situated in the center of the universe, while air and fire move outward toward the heavens. The cosmos is divided into two distinct spheres. The terrestrial sphere is characterized by change, force, and the movements of the four elements. The celestial on the other hand is unchanging, and the heavenly bodies are made of a fifth element, ether, which moves in perfect circles, thus accounting for the regular circular motions of stars and planets.

In general Aristotle's work is characterized by a lack of dogmatism and a willingness to adopt new methods to deal with the problem at hand. Later Aristotelianism produced influential systematic accounts of Aristotle's work, but these do not reflect the breadth of Aristotle's interests and approaches.


The early history of advanced geometry is little known, but hotly debated. The deductive-axiomatic method typical of Greek geometry appears to have developed in both mathematics and philosophy and it was probably practiced by Eudoxus in the late fourth century b.c.e. The first complete axiomatic work that has been preserved, however, is Euclid's (c. 325270 b.c.e.) Elements. Euclid presents geometry as a deductively ordered sequence of propositions derived from a set of indemonstrables. It is known to contain material from earlier mathematicians and its aim was probably to systematize known material rather than to present original work.

With Archimedes (287212 b.c.e.) the geometrical approach is developed and extended. Archimedes used the axiomatic method to explore new areas such as curvilinear figures; in Plane Equilibria and On Floating Bodies he also made the physical phenomena of statics and hydrostatics accessible to mathematical analysis. While Archimedes' work presents a series of rigorous geometrical proofs, he shows, in the Method, how many of the results were first found through a mechanical method.

Late antiquity was dominated by a mathematical tradition based on commentaries, which produced new classifications, systematizations, and definitions based on earlier work. Despite the dependence on earlier work, the treatises of mathematicians such as Pappus (fl. 320 c.e.) and Proclus (410485 c.e.) cannot be described as merely derivative.

At any time, the community of advanced practitioners was probably very small. Mathematics as a whole, however, was not a minority pursuit or isolated from the world. Mathematics included disciplines such as optics, mechanics, harmonics, and astronomy, and professions such as builders, astrologers, land measurers, tax collectors, and traders used and displayed mathematical knowledge for a variety of purposes.

Mechanics and Technology

It is often claimed that technology and science were completely separate activities in the ancient world, and that technology was marginalized and played a minor role in ancient society. This view, however, collapses when considering the relationship between mechanics and technology. Practical expertise, techne, however, often had to fight against associations with simple manual labor.

The discipline of mechanics in the ancient periods was concerned with the construction of machines, but it is uncertain to what extent the machines described were actually built. At times they were treated as mathematical objects and at times described as real machines. The earliest preserved mechanical treatise, Mechanical Problems, was written by a member of the Aristotelian school and answers an array of questions with reference to the principle of the lever. Later mechanical writers from Alexandria, such as Philo of Byzantium (c. 200 b.c.e.) and Hero of Alexandria (first century b.c.e.), wrote a large number of works on mechanical topics ranging from the construction of automatic theaters and mirror devices for temples to techniques for land measurement, lifting, and catapult construction. The mechanical treatises combined practical claims to efficacy with mathematical treatments demonstrating a close relationship between geometry, technology, and physics in this field.

While many of the devices described in mechanical treatises may have been pure invention, others were based on real machines. Technological invention and skill played important roles in construction work, land measurement, entertainment, and catapult construction. Catapults were becoming widespread in warfare from the fourth century b.c.e. and were central in sieges; and mechanical automata were used to induce wonder, for instance in religious processions. Images of instruments on gravestones and on wall paintings also testify that technology was part of society at a multitude of levels.


The use of the rising and setting of stars to mark seasons is described in literature from the sixth century and some Mesopotamian data were known in Greece certainly by the fifth century. In the fourth century Greek astronomy begins to focus on producing geometrical models of planetary movements based on uniform circular motion. The first known geometrical model of planetary motion is associated with Eudoxus (late fourth century), who also played a central role in the axiomatization of mathematics. Though his model was geometrically sophisticated, it deviated from observed facts in many respects, thus revealing an important aspect of early Greek astronomy; that it was concerned with producing geometrical models of planetary motion rather than with describing the physical cosmos.

The mathematical models were made more complex by the introductions of epicycles (a circle whose center moves on the circumference of another circle) and eccentric models (placing the earth off the center). Such techniques were used by Aristarchus of Samos (c. 280 b.c.e.), famous for proposing a heliocentric model of the world as well as the standard geocentric one, and were developed by Hipparchus of Nicea (fl. late second century) who began to use models to predict astronomical events.

Only little is known about the achievements of these writers as their work was eclipsed by Claudius Ptolemy's (c. 100170 c.e.) great oeuvre on astronomy, the Syntaxis (often known under its Arabic title Almagest ). Here, Ptolemy derives models for the planets, Sun, and Moon from first principles, using geometrical methods and observed data. In much of his work, Ptolemy mixed a geometrical approach with observation and an interest in physical mechanisms, carefully combining the rhetorical powers of mathematical precision with the status of Aristotelian physics. Ptolemy also wrote an important work on astrology, the Tetrabiblos, and in general astrological traditions flourished in the ancient Greek world.


Disease and its causes occupied a prominent place in Greek culture and thinking. It played central roles, for example in Homer's epic poems, in histories and in tragedies, and there exists evidence for a plurality of competitive practices ranging from inscriptions at temples to literary material with close ties to philosophy.

The main source on early medicine is a collection of medical treatises known as the Hippocratic corpus, which derives from many authors mainly from the fifth and fourth centuries. It is difficult to characterize this diverse collection of works, but the majority of the Hippocratic doctors were committed to explaining health and disease as physical phenomena. Authors recommend systematic approaches to diagnosis through close observation of symptoms and offered dietary regimes to maintain health. The treatise On the Nature of Man influentially described health as a balance between the humors: blood, yellow and black bile, and phlegm.

In Alexandria in the Hellenistic period anatomy and physiology changed through the work of Herophilus (c. 335280 b.c.e.) and Erasistratos (c. 304250 b.c.e.), who unusually for the Greek world based their work on human dissection. Later in this period different medical schools also emerged, which vigorously debated the relative merits of theory and practice in medicine; these debates are known mainly through Galen's somewhat biased accounts of them.

Galen of Pergamum (probably 130200 c.e.) shaped subsequent medical theory up until the renaissance and a vast number of his works has been preserved. Galen drew on material from many previous authorities, but explicitly attempted to reconcile the theories of the Hippocratics (for example, on the humors) with those of Plato (such as the tripartite division of the soul). He famously stated that the best doctor is also a philosopher and recommended demonstrative knowledge in medicine. He also, however, emphasized that a doctor must be good with his hands and he describes both surgery and dissections of animals in great detail.

See also Cosmology ; Geometry ; Islamic Science ; Physics ; Science ; Science, History of .


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Lloyd, Geoffrey E. R. Aristotelian Explorations. Cambridge, U.K.: Cambridge University Press, 1996. Discussions of a number of issues in Aristotle's thought.

Lloyd, Geoffery E. R., ed. The Hippocratic Writings. Harmondsworth, U.K.: Penguin, 1995. Translations with a general introduction.

Marsden, E. W. Greek and Roman Artillery. 2 vols. Oxford: Clarendon, 1971. Detailed account of the development of Greek and Roman artillery with translations of ancient texts on artillery-construction.

Netz, Reviel. The Shaping of Deduction in Greek Mathematics: A Study in Cognitive History. Cambridge, U.K.: Cambridge University Press, 1999. Important study of the development and characteristics of Greek deductive mathematics.

Nutton, Vivian. Ancient Medicine. London: Routledge, 2004. Accessible account covering the whole period.

Plato. Complete Works. Edited by J. M. Cooper. Indianapolis: Hackett, 1997.

Toomer, G. J., ed. and trans. Ptolemy's Almagest. Rev. ed. Princeton, N.J.: Princeton University Press, 1998. Commentary and translation.

Vlastos, Gregory. Plato's Universe. Oxford: Clarendon, 1975. Plato's theory of the cosmos.

Von Staden, Heinrich. Herophilus: The Art of Medicine in Early Alexandria. Cambridge, U.K.: Cambridge University Press, 1989. Translations with interpretive essays and an introduction on Alexandrian medicine.

Karin Tybjerg

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