The problem is that scale is completely smooth. IF there were some strict scale at which each theory applies, as I said, you'd then have problems for phenomena

The problem is that scale is completely smooth. IF there were some strict scale at which each theory applies, as I said, you'd then have problems for phenomena that straddle that scope. You can always add an extra electron or atom to a clump, so you'd have objects oscillating between obeying one set of equations vs the other, which seems very very very hard to actually believe. A similar problem actually exists in psychology vs sociology, though it seems you choose to ignore it. When you want to study the behavior of two human beings (say, a married childless couple), do you apply sociology or psychology? How about a married couple with children? An extended family? Also, psychology has to explain how an individual human behaves inside of a population, and sociology has to explain how the behavior of groups emerges out of the individual psychologies of their constituents. If they don't do this, then either one or both theories must be wrong. To take an extreme silly example, if psychology predicted that no person would never choose to kill themselves for the sake of another; but sociology predicted groups of people regularly have members sacrificing themselves for the group - then one of the theories must be wrong, you can't just say "we apply one theory when talking to a man and another when talking about the group".