Aristotle
Born: 384 BCE (Stagira, Greece), Died:
322BCE (Chalcis, Greece)
Aristotle (Greek: Aristoteles) was an ancient Greek philosopher and scientist, and one of the greatest intellectual figures of Western history. He was the author of a philosophical and scientific system that became the framework and vehicle for both Christian Scholasticism and medieval Islamic philosophy.
Aristotle’s intellectual range was vast, covering most
of the sciences and many of the arts, including biology, botany, chemistry,
ethics, history, logic, metaphysics, rhetoric,philosophy of mind, philosophy of
science, physics, poetics, political theory, psychology, and zoology.
He was the founder of formal logic, devising for it a
finished system that for centuries was regarded as the sum of the discipline.
Aristotle also pioneered the study of zoology, both observational and
theoretical, in which some of his work remained unsurpassed until the 19th
century. His writings in metaphysics and the philosophy of science continue to
be studied, and his work remains a powerful current in contemporary philosophical
debate.
Physics and Metaphysics
Aristotle divided the theoretical sciences into three
groups: physics, mathematics, and theology. Physics as he understood it was
equivalent to what would now be called “natural philosophy,” or the study of
nature; in this sense it encompasses not only the modern field of physics but
also biology, chemistry, geology, psychology, and even meteorology.
Metaphysics, however, is notably absent from
Aristotle’s classification; indeed, he never uses the word, which first appears
in the posthumous catalog of his writings as a name for the works listed after
the Physics. He does, however, recognize the branch of philosophy now called
metaphysics. He calls it “first philosophy” and defines it as the discipline
that studies “being as being.”
Aristotle’s contributions to the physical sciences are
less impressive than his researches in the life sciences. In works such as On
Generation and Corruption and On the Heavens, he presented a world-picture that
included many features inherited from his pre-Socratic predecessors.
From Empedocles
(c. 490–430 BCE) he adopted the view that the universe is ultimately composed
of different combinations of the four fundamental elements of earth, water,
air, and fire. Each element is characterized by the possession of a unique pair
of the four elementary qualities of heat, cold, wetness, and dryness: earth is
cold and dry, water is cold and wet, air is hot and wet, and fire is hot and
dry. Each element also has a natural place in an ordered cosmos, and each has
an innate tendency to move toward this natural place.
Thus, earthy solids naturally fall, while fire, unless
prevented, rises ever higher. Other motions of the elements are possible but
are considered “violent.” (A relic of Aristotle’s distinction is preserved in
the modernday contrast between natural and violent death.)
Aristotle’s vision of the cosmos also owes much to
Plato’s dialogue Timaeus. As in that work, the Earth is at the centre of the
universe, and around it the Moon, the Sun, and the other planets revolve in a
succession of concentric crystalline spheres. The heavenly bodies are not
compounds of the four terrestrial elements but are made up of a superior fifth
element, or “quintessence.” In addition, the heavenly bodies have souls, or
supernatural intellects, which guide them in their travels through the cosmos.
Even the best of Aristotle’s scientific work has now
only a historical interest. The abiding value of treatises such as the Physics
lies not in their particular scientific assertions but in their philosophical
analyses of some of the concepts that pervade the physics of different eras—
concepts such as place, time, causation, and determinism.
Philosophy of Science
In his Posterior Analytics, Aristotle applies the
theory of the syllogism (a form of deductive reasoning) to scientific and
epistemological ends (epistemology is the philosophy of the nature of
knowledge). Scientific knowledge, he urges, must be built up out of
demonstrations. A demonstration is a particular kind of syllogism, one whose
premises can be traced back to principles that are true, necessary, universal,
and immediately intuited.
These first, self-evident principles are related to
the conclusions of science as axioms are related to theorems: the axioms both
necessitate and explain the truths that constitute a science. The most
important axioms, Aristotle thought, would be those that define the proper
subject matter of a science. Thus, among the axioms of geometry would be the
definition of a triangle. For this reason much of the second book of the Posterior
Analytics is devoted to definition.
The account of science in the Posterior Analytics is
impressive, but it bears no resemblance to any of Aristotle’s own scientific
works. Generations of scholars have tried in vain to find in his writings a
single instance of a demonstrative syllogism. Moreover, the whole history of
scientific endeavour contains no perfect instance of a demonstrative science.
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