students, ANAXIMANDER and ANAXIMENES. Present-day knowledge of this MILESIAN
SCHOOL is based on fragments attributed to them by later writers. These first
philosophers were metaphysicians, seeking for an element or force behind
appearance that explained everything. Thales said that all was ultimately
water, Anaximander that it was boundless or the infinite, and Anaximenes that
it was air. Subsequent Greek philosophers, such as HERACLITUS and PARMENIDES,
argued about whether change or permanence was the basic feature of the world
and about whether one or more than one element was the fundamental constituent
of reality (see MONISM; PLURALISM). Greek philosophy before Socrates was
principally concerned with these metaphysical questions.
Socrates.
Socrates, an Athenian, was primarily interested in value questions that
affected what a person should do. At the time in Athens, the paid teachers,
the SOPHISTS, taught people how to live successfully; they did not raise the
Socratic question of what was the right way of life, however. Socrates did not
write anything, but he is vividly portrayed by his pupil Plato in the Dialogues
as being the “gadfly” of Athens, forever asking people why they are doing what
they are doing and making people realize that general principles were necessary
to justify their conduct. Socrates was finally arrested and accused of heresy
and corrupting the young of Athens. Socrates used his trial, described in
Plato’s Apology, as a final opportunity to make his general point. His
accusers, he showed, did not know what the charges actually meant and had no
evidence for them. He reported that the Delphic oracle had said that he,
Socrates, was the wisest of all of the Athenians. Socrates said he was the
wisest because he alone knew nothing and knew that he knew nothing, whereas
everybody else thought they knew something. In spite of his eloquence and
wisdom, Socrates was convicted and sentenced to death.
Plato.
After Socrates’ execution, his disciple Plato developed the first comprehensive
philosophical system and founded the Academy, the first formal philosophical
school. Plato contended that knowledge must be of universals (that is, of
general types or kinds) and not of particulars. To know a particular cat,
Miranda, the individual must first know what it is to be feline in general.
Otherwise he or she will not be able to recognize the particular feline
characteristics in Miranda. These universals, Plato claimed, were the basic
elements from which the world was formed. They are called the Forms, or
Platonic Ideas. Mathematics provides the most obvious cases of these Forms.
They are known not by sense perception but by reasoning. They are known by the
mind, not by the bodily organs. The world of Platonic Ideas is the unchanging
Forms of things. The philosopher should turn away from this world of
appearance and concentrate on the world of Forms. Plato, in his most famous
work, The Republic, said that the world would be perfect when philosophers are
kings and kings are philosophers. He believed that the philosopher-kings would
know what justice really is, and, based on their knowledge of the Forms, they
could then achieve justice in all societies.
For Plato the ultimate Idea, which illuminated the rest of the pure ideas, was
the Idea of the Good. As Plato grew older he became more mystical about this
idea. The school of NEOPLATONISM, which began a few centuries after his death,
stressed these otherworldly and mystical elements, identifying the idea of the
Good with God.
Aristotle.
Plato’s leading student, Aristotle, developed the most comprehensive
philosophical system of ancient times. Aristotle broke with Plato, stressing
the importance of explaining the changing world that humankind lives in as
opposed to the Platonic Ideas. Aristotle spent years studying the natural
sciences and collecting specimens, and about 90 percent of his writings are on
scientific subjects, mostly on biological ones. Aristotle believed he could
account for the changes and alterations in this world without either having to
deny their reality or having to appeal to another world. For Aristotle all
natural objects were composed of form and matter, and the changes that take
place in matter are the substitution of one form for another. This
substitution takes place because every natural object has a goal, or telos,
which it is its nature to achieve. Thus stones, because they are essentially
material, seek the lowest point, which is why they fall down. Each species is
ultimately trying to achieve a state of perfection which for Aristotle was a
state of perfect rest. The cosmos, as Aristotle saw it, is an ordered striving
for this perfection. The pinnacle of the order is the Unmoved Mover, the
ultimate cosmic agent, which fully and perfectly realizes its essence of
eternal thought. The heavenly spheres imitate the Unmoved Mover and by so
doing set the heavens in an eternal spherical motion; this process is repeated
by individual souls, and so on. Aristotle’s vision of the Cosmos remained
central to Western thought until the time of Nicolaus Copernicus.
Hellenistic and Roman Periods.
In the period from about 300 BC to AD 200 the central philosophical concerns
shifted to how an individual should conduct his or her life. The Stoics, the
Skeptics (see SKEPTICISM), and the Epicureans (see EPICUREANISM), although they
dealt with the classical epistemological and metaphysical issues, emphasized
the question of how humans should conduct themselves in a miserable world. All
these theories stressed withdrawal, whether physical, emotional, or
intellectual, from the turmoils of the day.
Medieval Period.
Greek philosophy was the major formative influence on the later philosophical
traditions of Judaism, Islam, and Christianity. In all three, the theories of
the Greeks, particularly Plato and Aristotle, were employed to clarify and
develop the basic beliefs of the religious traditions.
PHILO OF ALEXANDRIA introduced Platonic ideas and methods into Jewish thought,
particularly into the interpretation of Scripture about the beginning of the
Christian era. He exerted little influence on later Jewish thought, however,
and the Jewish philosophy of the Middle Ages seems to have developed as a
movement parallel to those in Islam. Important figures in early medieval
Jewish thought include Isaac Israeli, SAADIA BEN JOSEPH GAON, and the
Neoplatonist Solomon IBN GABIROL. The most important Jewish thinker of the
Middle Ages, however, was MAIMONIDES. Maimonides developed a comprehensive
interpretation of religion and understanding based on Aristotelian principles
that was influential in the Christian West as well as among Jewish thinkers.
In Judaism, as in Islam and Christianity, religious speculation and philosophy
developed in close connection. This development is particularly evident in the
Jewish mystical tradition, the KABBALAH. The esoteric teachings of these
schools have influenced much later Jewish thought, including that of Spinoza,
the most important Jewish philosopher of the early modern period. Drawing both
on his religious background and on the geometric method of Descartes, Spinoza
developed a philosophical PANTHEISM of great depth.
In the Islamic tradition as well the starting point was the work of Plato and
Aristotle. The 9th-century Neoplatonist al-KINDI was followed by al-FARABI,
who drew on both Plato and Aristotle to create a universal Islamic philosophy.
The most important of the medieval Muslim philosophers, however, was Avicenna
(ibn Sina). Starting from the distinction between essence and existence,
Avicenna developed a metaphysics in which God, the necessary being, is the
source of created nature through emanation. Both his metaphysics and his
intuitionist theory of knowledge were influential in the later Middle Ages as
well as in the later history of Islamic thought.
The philosophical tradition did not go unchallenged, however. The 11th-century
theologian and mystic al-GHAZALI mounted a critique of philosophy, specifically
Avicenna’s, that is rich in argument and insight. Al-Ghazali’s Incoherence of
the Philosophers provoked a response by AVERROES ibn Rushd entitled the
Incoherence of the Incoherence, in which al-Ghazali’s arguments are countered
point for point. Averroes was best known, however, as an interpreter of
Aristotle and excited great influence on all subsequent thinkers in the
Aristotelian tradition. In the later Middle Ages the historian and philosopher
IBN KHALDUN produced a trenchant critique of culture, and the elaboration of
metaphysics and epistemology was carried on in the theosophical schools of
Islamic mysticism.
The first systematic Christian philosophy was that of ORIGEN, but for the
European Middle Ages no authority could rival Saint Augustine. Augustine
elaborated a Neoplatonist vision combining the metaphysics of PLOTINUS with an
elaboration of the Christian doctrine of the Trinity. To this he added an
epistemology in which knowledge is achieved through illumination by grace. No
substantial movement arose beyond Augustine until the 12th century, when new
interest arose in logic and theory of knowledge. In this connection the most
important figures are Saint ANSELM and Peter ABELARD.
In the late 12th and early 13th centuries the writings of Aristotle were
reintroduced into the West, first in translations from the Arabic and later in
direct translation. After some initial resistance Aristotle became the
dominant philosophical authority and remained so until the Renaissance. First
Saint ALBERTUS MAGNUS and then Saint Thomas AQUINAS combined Aristotle’s
philosophy with the tradition of Augustinian theology to produce a synthesis
holding that Aristotle was right about those things that are within the grasp
of reason, while what was beyond reason could only be known by faith. Thus
reason could prove that God exists, but his nature could be known only by
faith. More extreme Aristotelian schools developed and came into conflict with
the church, which, in 1277, issued condemnations of many positions held by
Aristotle and Aquinas, among others. In the 14th century two figures dominated
the scene: DUNS SCOTUS and WILLIAM OF OCCAM. Scotus developed an extemely
complex philosophy based on a number of earlier positions, and Occam’s
critiques of metaphysics and epistemology remain paradigms of philosophical
argument.
Rationalism.
The synthesis of Christianity and Aristotelianism was a major form of
SCHOLASTICISM, which dominated European philosophy into the 17th century.
During the Renaissance other forms of ancient philosophy began to be revived
and used as ammunition against the scholastics. This involved the Renaissance
Platonists and the Skeptics, as well as others interested in esoteric doctrines
like that of the Kabbalah. In terms of the future development of philosophy,
the revival of ancient skepticism played the greatest role. This view,
popularized by Montaigne in the late 16th century, raised the fundamental
epistemological problem of what can be known. The methods of the new
scientific schools conflicted with, and thus brought into question, the
principles inherited from the Middle Ages. Rene Descartes proposed a method
for guaranteeing knowledge. He argued that in order to provide a secure
foundation for knowledge it was necessary to discover “clear and distinct
ideas” that could not be doubted and could serve as a basis for deriving
further truths. He found such an idea in the proposition “I think, therefore I
am.” Using this as a paradigm, Descartes drew a distinction between thinking
substance and extended substance, or mind and matter. He went on to draw
conclusions about God, nature, and mind that continue to be influential. For
this reason Descartes is often considered the founder of modern philosophy.
A few years after Descartes’s death, Baruch de Spinoza offered his theory to
improve on that of Descartes. Spinoza insisted that only one substance, God,
exists, and that two of his attributes are thought and extension. Everything
that is and that can be known about is an aspect of God. Spinoza’s God,
however, was the antithesis of the God of traditional religion. God, or Nature
(as Spinoza put it), was the laws from which everything followed. In Spinoza’s
pantheistic world everything had to be what it was, and everything was to be
understood rationally. The mind and body were two aspects of the same thing,
which was to be understood either logically or in terms of natural science. A
third great 17th-century rationalist was Gottfried Wilhelm von Leibniz. The
basic unit of his metaphysics, equivalent to a substance, was the monad, a
center of force or energy. Each monad was internally determined by its
definition. Monads could not interact, but, due to a “preestablished harmony,”
the action in one monad coincided with that in another. God chose the monads
in the world s