[Physics] Logical connection of Newton’s Third Law to the first two

forcesnewtonian-mechanics

The first law and second laws of motion are obviously connected. But it seems to me that the third law is not related to the first two, at least logically.

(In Kleppner's Mechanics the author states that the third law is a necessity to make sense of the second law. It didn't make sense to me, though. I'll post the excerpt if anyone would like to see it.)

EDIT:
Excerpt from Introduction to Mechanics by Kleppner & Kolenkow (1973), p. 60:

Suppose that an isolated body starts to accelerate in defiance of
Newton's second law. What prevents us from explaining away the
difficulty by attributing the acceleration to carelessness in
isolating the system? If this option is open to us, Newton's second
law becomes meaningless. We need an independent way of telling whether
or not there is a physical interaction on a system. Newton's third law
provides such a test. If the acceleration of a body is the result of
an outside force, then somewhere in the universe there must be an
equal and opposite force acting on another body. If we find such a
force, the dilemma is resolved; the body was not completely isolated.
[…]

Thus Newton's third law is not only a vitally important dynamical
tool, but it is also an important logical element in making sense of
the first two laws.

Best Answer

Newton's Fist and Second Law relate forces acting on a single system to conservation or changes of that system's momentum. It doesn't say anything about the nature of these forces, their origin; they could come "out of nowhere" and Laws 1 and 2 still hold.

The Third Law, however, indicates that all forces, or "actions", are just one side of an interaction. This view, that systems act on each other, by either attracting or repelling each other, still holds even in circumstances where other aspects of newtonian mechanics don't (i.e. relativistic or quantum mechanics). All forces observed since Newton's time until today are still modelized as being the results of the fundamental interactions.

One could say that the First Law describes the nature of momentum, the Thid Law the nature of forces, and the Second Law the link between the two. The First and Third Law thus provide the setting where the Second Law is stated.