Note 61 — VII
Reading edition
Newton's "Rules for Philosophizing" (Principia, Book III) are as follows:
Rule I. "No more causes of natural things are to be admitted than such as are both true, and sufficient to explain the phenomena of those things."
Rule II. "Natural effects of the same kind are to be referred as far as possible to the same causes."
Rule III. "Those qualities of bodies that can neither be increased nor diminished in intensity, and which are found to belong to all bodies within reach of our experiments are to be regarded as qualities of all bodies whatever."
Rule IV. "In experimental philosophy propositions collected by induction from phenomena are to be regarded either as accurately true or very nearly true notwithstanding any contrary hypothesis, till other phenomena occur, by which they are made more accurate or are rendered subject to exceptions."