ABSTRACT
From the days of Aristotle to those of Descartes and Kant the fundamental questions of physics supplied much of the stimulus and substance of philosophical reflection. If only extension and motion are truly existent in nature, and colours, tastes, temperatures, etc., are mere subjective products, then a true physics can be had only by reducing all phenomena to those of motion. The significance of the obvious truth, that logical or hypothetical necessity holds of nature, has been obscured by a number of powerful dogmas in modern philosophy which are certainly not the outgrowth of reflection on the nature of modern physics. Nineteenth century physics had succeeded in systematizing our knowledge of inorganic nature into two divisions, mechanics and electricity, the former governed by Newton’s laws, and the latter by Max-well’s equations. The principle of causality is thus simply the general maxim that physical phenomena are connected according to invariant laws.
