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Physics of the Greeks

The Natural Philosophy of Aristotle


Physics of the Greeks

Aristotle, by Francesco Hayez, 1811

Physics of the Greeks - Index

  • Before Aristotle
  • Physics of Aristotle
  • Archimedes, Hipparchus, & Ptolemy


    The Natural Philosophy of Aristotle

    While his mentor Plato (and his mentor, Socrates) were far more concerned with moral philosophy, Aristotle's (384 - 322 B.C.E.) philosophy had more secular foundations. He promoted the concept that observation of physical phenomena could ultimately lead to the discovery of natural laws governing those phenomena, though unlike Leucippus and Democritus, Aristotle believed that these natural laws were, ultimately, divine in nature.

    His was a natural philosophy, an observational science based on reason but without experimentation. He has rightly been criticized for a lack of rigor (if not outright carelessness) in his observations. For one egregious example, he states that men have more teeth than women which is certainly not true.

    Still, it was a step in the right direction.

    The Motions of Objects

    One of Aristotle's interests was the motion of objects:
    • Why does a rock fall while smoke rises?
    • Why does water flow downward while flames dance into the air?
    • Why do the planets move across the sky?

    He explained this by saying that all matter is composed of five elements:

    • Fire
    • Earth
    • Air
    • Water
    • Aether (divine substance of the heavens)

    The four elements of this world interchange and relate to each other, while Aether was an entirely different type of substance. These worldly elements each had natural realms. For example, we exist where the Earth realm (the ground beneath our feet) meets the Air realm (the air all around us and up as high as we can see).

    The natural state of objects, to Aristotle, was at rest, in a location that was in balance with the elements of which they were composed. The motion of objects, therefore, was an attempt by the object to reach its natural state. A rock falls because the Earth realm is down. Water flows downward because its natural realm is beneath the Earth realm. Smoke rises because it is comprised of both Air and Fire, thus it tries to reach the high Fire realm, which is also why flames extend upward.

    There was no attempt by Aristotle to mathematically describe the reality that he observed. Though he formalized Logic, he considered mathematics and the natural world to be fundamentally unrelated. Mathematics was, in his view, concerned with unchanging objects that lacked reality, while his natural philosophy focused upon changing objects with a reality of their own.

    More Natural Philosophy

    In addition to this work on the impetus, or motion, of objects, Aristotle did extensive study in other areas:
    • created a classification system, dividing animals with similar characteristics into "genera."
    • studied, in his work Meteorology, the nature not only of weather patterns but also geology and natural history.
    • formalized the mathematical system called Logic.
    • extensive philosophical work on the nature of man's relation to the divine, as well as ethical considerations

    Aristotle's work was rediscovered by scholars in the Middle Ages and he was proclaimed the greatest thinker of the ancient world. His views became the philosophical foundation of the Catholic Church (in cases where it didn't directly contradict the Bible) and in centuries to come observations that did not conform to Aristotle were denounced as heretic. It is one of the greatest ironies that such a proponent of observational science would be used to inhibit such work in the future.

    Physics of the Greeks - Index

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