If Earth attracts the Moon with gravitational force, then according to 3,rd Newton's law the Moon attracts the Earth with the same but opposite force. But what if someone argues that the Moon attracts the Earth anyway due to its own gravitation, can we really say that it's the reaction force? Another example: You push the car. Here the action force is electromagnetic. The car pushes you back and it's the reaction force, electromagnetic. So it seems that action and reaction must be the forces of the same nature. But what if someone uses the same argument here, and explains the third Newton law like this: When you push the car, the action force is electromagnetic. Because of the inertia of the car, it oposes the push and you feel the reaction force. Thus, here the reaction force is the force of inertia and is therefore of different nature than the action force. So two questions: 1 Is this explanation of the 3.rd Newtons law better than the first one? 2 Can gravitational force really be force of reaction?