Solid, liquid, gas.

Ok, in fact there are many more: plasmas, quark-gluon plasma, Rydberg matter, Bose-Einstein condensates and fermionic condensates, quantum spin Hall state, degenerate matter, strange matter, superfluids and supersolids, and possibly string-net liquids. (This list was taken from the Wikipedia article on state of matter.) But why are there any discrete states at all? Why is there not just one continuous level of “blurriness”? Maybe with one or two other dimensions to describe the state.

I couldn’t find an explanation on the Wikipedia page but I assume this is simple stuff (as long as one doesn’t continue to ask “why” too often). With atoms I’m fairly ok with the discrete level of states/orbits for the electrons. “That’s just the way it is.” Or at least the explanation is on a low enough level for me to swallow it and not to ask any further.

But the state of matter is an inter-atom/inter-molecular thing (it doesn’t make sense, I think, to say that an individual atom or molecule is in solid state) and it should somehow be possible to derive an explanation form the description of individual molecules (just as one can make statements about which molecules will form by only looking at the individual  atoms). Where does this additional discreteness of our existence come from? Can anybody point me in the right direction? Maybe this is standard A-level chemistry/physics stuff.

Why is all matter limited to a discrete set of states?