1. Review of Plato Plato impressed with the divine origin of the cosmos Therefore bore imprint of mind – φ can be saved Not interested in individual things for their own sake

2. Aristotle Life (384-322 B.C.E) studied at Plato’s Academy for twenty years until Plato’s death in 348 tutor to King Philip of Macedonia’s thirteen year old son Alexander (i.e. he Great) Athens 335 B.C founds the Lyceum, his own school

3. Aristotle’s theory of causes Aristotle has a different emphasis, one that combines forms and senses 1. Formal cause – from Plato, but not sufficient in itself 2. Material cause 3. Efficient cause 4. Final cause What explains the possibility of a table? Observation, but not experiment from observation of world of the senses

4. Aristotle’s theory of matter 4 elements of (terrestrial) matter Earth Air Fire Water

5. Aristotle’s theory of matter Fundamental qualities of terrestrial matter The doctrine of natural place Fundamental difference between earth and heavens HotCold DryWet

6. Aristotle’s physics of motion Aristotle’s axiom: All motion requires a mover Natural motion – doctrine of natural place Violent motion – animate vs inanimate bodies For Aristotle (and for us) rest does not require an explanation. Is a natural state Speed and force are mutually and directly proportional Speed is inversely proportional to resistance Vs. (v α F and F α v) (v α 1/R)

7. Aristotle criticized Eudoxus’s explanation of planetary motions He ended up with 55 spheres

8. Two innovations introduced between Aristotle and Ptolemy to improve fit The eccentric circle C E P A B DF Attributed to Apollonius of Perga ~20 -190 BCE)

9. Two innovations introduced between Aristotle and Ptolemy to improve fit The epicycle on deferent

10. Questions 3. Why, according to Aristotle, do bodies fall? 2.Which of the Greek beliefs, if any, about how phenomena of the physical world should be explained do we hold today? 1. How do the Greeks contrast with the ancient Near Eastern thinkers regarding explanations of the motions of the heavens? 4. Why, according to Plato, must planetary motions be rationally explainable? 5.What aspects of Aristotle’s theory of motion do we accept today and what do we reject? 6. Why has someone said: “Everybody is born either a Platonist or an Aristotelian”