What are an object's decomposition criteria?

Question

What reasoning, or probably concrete criteria, is behind a definition of what parts an object consists of? Does it depend on desired object behavior? Is there a kind of "carving Object at its joints" thing?

I've already read some posts on mereology, but they are quite heavy for me to digest. It seems that an answer is somewhere there though.

Talking about a purpose I pursuit, I'd like to find some philosophical ideas which correlate with an OOP concept called composition. I have my way of composing objects though, which is providing an object with all necessary resources in order for it to be able to do its job which is reflected in a class method. For example, when I model a database table row, I realize that is can't exist without a connection to a database and a query that results in exactly this row. So I put them in a TableRow constructor. The point here is that domain modeling goes first. So I start with "carving nature at its joints", identifying abstractions, then turn them into a programming concept called interface. Then I want to identify concrete things, which are classes. When I'm done with it, I have to decide what a concrete class should be composed of, since very rarely it does all the job by itself. Once again, all this endeavor lies in a problem space context. It has nothing to do with programming itself. So I thought metaphysics has some answers. Mereology could be a more concrete area, but at the moment I haven't found anything of any particular use.

Answer 1

I think you are asking what it means for something to be a 'system'. A system typically has component parts or entities that are combined and structured in a particular way so that the system as a whole has properties that the individual parts do not. A system may be artificial, in which case it will usually have an intended function or purpose, or it may be natural, in which case it may appear to have purposeful behaviour that is the result of adaptation. A clock is a system because it can tell you the time, provided it is assembled correctly, while a collection of clock parts cannot. A human being is a system: it can do all kinds of things such as enjoy music and fall in love, while the individual body parts cannot. More abstract things like economies, institutions, or environments can also be called systems if they have properties or behaviours that emerge from the way their components interact. The study of the properies of systems is called systems theory or systems science.

On the other hand, if you are asking about the logic that describes the relationships between parts and wholes, this is called mereology.