INTROD UCTION TO SOCIOL OGY 6 1 1
idea of statics, of a state of equilibrium. In fact, mechanical statics shows us the conditions of equilibrium of any system whatever. It is natural enough that economists, political theo- rists, and sociologists have attempted to reduce the scientific explanation of societies to purely mechanical laws ; likewise, that others have tried to reduce it to purely mathematical laws. This historical process is logical, but these explanatious, pre- cisely because of their too general and too abstract character, go outside of the sociological domain, and are insufficient. They are comprised more properly within the subject of general philoso- phy. They can and must be used by general philosophy, but not by the special philosophy of the social sciences.
Nevertheless, it is correct to include under the denomination of forces, not only the mechanical properties, but also the organic and superorganic properties of matter. In order to examine the problem of social equilibrium, it is necessary, first, to have the idea of mechanical equilibrium as it presents itself in inorganic matter; then, to pass to organic matter; finally, to pass to superorganic matter.
It is to be remarked that the transition from one of the lower of these three different forms under which matter presents itself to the succeeding higher form is effected in an uninterrupted manner, by insensible degrees, and not by abrupt leaps. In a word, it is an evolutionary passage from the one to the other. It follows that, in the lowest forms of organisms, equilibration is still preponderantly effected among forces which are chiefly mechanical.
Let us recall that mechanics rests upon three fundamental principles or properties of matter, principles which are demon- strable by experimental observation, and which are involved in every industrial application of mechanics. These principles are : first, the law of inertia; second, that of the independence of the effects of forces; third, that action and reaction are equal.
The first is sufficiently known ; as to the second, it expresses that the effect of a force upon a body is always the same, what- ever may be the velocity of the body, and whatever may be the other forces which impel it. If the body changes, the effect
