[monkeycantype]

somewhere on the internet are some videos in which an italian scientist describes what he means by a system. I think that's probably enough to google. So if you're willing to accept that sometimes we are able to recognise a phenomenon that fits our definition of a category, even though we are not capable of explicitly defining that category, then we could say that a cell fits out intuitive definition of a system, even though I think despite being employed as system achitect, I'm not sure I could tell you what a system is. I like the attempts at definitions of living systems that discuss phenomenon that enable the persistence of information that are robust against the entropy.

Anywhy on to my attempt at answering your question:

If we could identify a set of molecules in the pores of vent rock back in the early pre-biotic earth, each with a distinct catalytic function, that were the using energy available, perhaps as electric charge, perhaps chemical energy and interacting to replicate that same set of molecules in neighbouring pores, then we could look at the actions of each molecule, and determine how each molecule participates in the chemical processes that result in the replication of the whole set of molecules. If a molecule is mutually dependent on on other molecules in the set for their mutual replication, I think we can call them a contributing part of the system. If a molecule depends on the other molecules to be replicated, but the replication of no other molecule is improved from its presence in the set, then it is not a contributing part of the system, but a freeloader.

I think this sets up two maximal strategies:

A system is most efficient if it has no freeloaders.

A molecule is most efficient if it can freeload.