Aristotle :: essays research papers

To the modern reader, Aristotles pictures on astronomy, as presented in Metaphysics, Physics, De Caelo (On the Heavens) and Simplicius Commentary, testament most likely seem very bizarre, as they are base more on a priori philosophical speculation than empirical observation. Although Aristotle acknowledge the importance of "scientific" astronomy - the study of the positions, distances and motions of the stars - he nevertheless case-hardened astronomy in the abstract, linking it to his overall philosophical world picture. As a result, the modern distinction between physics and metaphysics is non present in Aristotle, and in order to fully appreciate him we must try to abandon this pre-conception. Aristotle argued that the universe is spherical and finite. Spherical, because that is the most perfect shape finite, because it has a center, that is to say the center of the creation, and a body with a center cannot be infinite. He believed that the earth, too, is a sphere . It is relatively small compared to the stars, and in contrast to the celestial bodies, of all time at rest. For one of his proofs of this latter point, he referred to an empirically testable fact if the earth were in motion, an observer on it would see the fixed stars as moving, well(p) as he now observes the planets as moving, that is from a stationary earth. However, since this is not the case, the earth must be at rest. To prove that the earth is a sphere, he produced the argument that all earthly substances move towards the center, and thus would eventually take aim to form a sphere. He also used severalize based on observation. If the earth were not spherical, lunar eclipses would not channelize segments with a curved outline. Furthermore, when one travels northward or southward, one does not see the same stars at night, nor do they occupy the same positions in the sky. (De Caelo, Book II, chapter 14) That the celestial bodies must also be spherical in shape, can be dete rmined by observation. In the case of the stars, Aristotle argued that they would have to be spherical, as this shape, which is the most perfect, allows them to retain their positions. (De Caelo, Book II, chapter 11) By Aristotles time, Empedocles view that there are four basic elements - earth, air, fire and water - had been for the most part accepted. Aristotle, however, in addition to this, postulated a fifth element called aether, which he believed to be the main constituent of the celestial bodies.