A related statement is:
In a closed system, the sum of the (net) forces acting on the particles is zero.
This statement is "almost" equivalent to Newton's 3rd law. It certainly holds in Newtonian mechanics, so it is implied by the 3rd law and in the case of ony two particles in the system it reduces to it. However, it does not say anything about where the forces come from.
In a way, that is very appealing. The only thing we can actually observe about a particle is the net force (by measuring its acceleration). We can not tell which particle is exerting that force. Thus the above statement is a generalised version of the 3rd law: it admits both theories that assign forces between individual pairs of particles (like Newtonian mechanics does), and those that don't.