Constellations and Conjectures

1. Front Matter

   Pages I-X

   PDF

2. Part I

   1. Cosmological Explanation, B.C.

      • Norwood Russell Hanson

      Pages 1-1

   2. The Conceptual Content of Book One, Part I

      • Norwood Russell Hanson

      Pages 3-3

   3. Introduction

      • Norwood Russell Hanson

      Pages 5-6

   4. The Historical Content of Book One, Part I

      • Norwood Russell Hanson

      Pages 7-31

   5. Plato

      • Norwood Russell Hanson

      Pages 33-39

   6. Eudoxos and ‘Plato’s Problem’

      • Norwood Russell Hanson

      Pages 41-60

   7. Aristotle

      • Norwood Russell Hanson

      Pages 61-88

3. Part II

   1. Ptolemy and Prediction

      • Norwood Russell Hanson

      Pages 89-97

   2. Pre-Ptolemaic Anticipations

      • Norwood Russell Hanson

      Pages 99-112

   3. Appendix

      • Norwood Russell Hanson

      Pages 113-134

   4. Three Dimensional Variations of Ptolemy’s Technique

      • Norwood Russell Hanson

      Pages 135-140

4. Part I

   1. The Medieval Rediscovery of Ptolemy’s Tool Box

      • Norwood Russell Hanson

      Pages 141-141

   2. ‘The Ptolemaic System’

      • Norwood Russell Hanson

      Pages 143-165

   3. Supplementary Material for Book Two, Section A

      • Norwood Russell Hanson

      Pages 166-172

5. Part II

   1. Copernicus’ Systematic Astronomy

      • Norwood Russell Hanson

      Pages 173-199

   2. Further Aspects of Copernican Astronomy in Contrast to All that had Gone Before

      • Norwood Russell Hanson

      Pages 200-235

   3. Supplement to Section on Copernican Theory

      • Norwood Russell Hanson

      Pages 236-249

6. Part I

   1. Kepler and the ‘Clean’ Idea

      • Norwood Russell Hanson

      Pages 251-276

   2. Supplementary Material for Book Three, Part I

      • Norwood Russell Hanson

      Pages 277-282

An occurrence is explained by being related to prior events through known laws. Other intellectual activities may also constitute explanation - but this much certainly does. Ideally, an explained occurrence (0) could have been predicted in a connected way - by extrapolation from prior events (e) via the same laws (L). Schematically, 1 Explanation: 0 -Lt, 2, 3-(e e e )'-AI t 2 3 01 Prediction: (e e e )I-L , 2, 3_ +.11 t 2 3 t Thus Mars' backward loop in late summer, 1956, is explained by showing how this follows from (e ) its mean distance from sun and earth, (e ) its t 2 mean period of revolution, (e ) its past positions relative to earth, etc. 3 - by way of the laws of Celestial Mechanics (including (Lt) Kepler's Laws and Galileo's, (L2) Newton's, and (L3) those of Laplace and Lagrange. Moreover, this loop (0) could have been predicted from such events (e -e ) via the laws of Celestial Mechanics. t 3 This is an ideal situation. It crystallized late in the history of planetary theory.The Greeks found explanations for heavenly motions: the back­ ward loops were explained to their satisfaction. But they could not predict these motions, not in terms of Attic explanatory cosmologies.

• Aristotle
• Medieval Literature
• Plato
• astronomy
• concept

• Evergreen State College, Olympia, USA

  Willard C. Humphreys

Policies and ethics