"Galileo's principle of inertia a m.p. that is present alone in space not acted upon by other bodies moves without acceleration. (a) In a certain sense, this law is an empirical law; (billiard ball, railway car). Strictly speaking, however, it has the character of a definition. For we say that other bodies do not act on a body if this body moves uniformly in a straight line. But for all practical purposes the law can be designated as empirical, because experience happens to be such that the law can be carried out or maintained without any artificial-looking assumptions.
(b) But this law does not hold for an arbitrary state of motion of the c.s. But it holds to a certain degree of approximation for systems at rest relative to the earth, and to an even closer approximation for a system whose origin is at rest relative to the center of gravity of the solar system, and whose axes are directed permanently toward 3 fixed stars."
О втором з-не Ньютона:
"The equations of motion given above have the character of definitional equations for the force, thus they can be neither confirmed nor refuted by experience. Nonetheless, we could find ourselves compelled by experience to abandon them; this would happen dbc if the description of facts by means of the equations m - = X . . would lead to our dt2 having to assume expressions for the force components X . . . in a very complicated manner. One would then reject the equations of motion as unsuitable. Example: identical springs, stretched in the same way, act in the same direction upon a free body. If the acceleration were not proportional to the number of springs acting, then it would follow from the equations that the force would also not be proportional to the number of springs. This does not represent a logical contradiction, but it would [p. 9] result in our presuming that we could arrive at a simpler, i.e., preferable theory of motion, if we based ourselves on other equations of motion."
Так эмпирический з-н или определение!?! Формально - определение. Но по сути - опытный закон, поскольку такое oпределение осмысленно лишь пока оно работает на практике.
Нехило, да? То есть логическое (неопровержимое опытом) и эмпирическое не противопоставлено. Логическое определение имеет смысл, пока оно работает для эмпирических данных. Хотя формально опытом не опровергается, а?