As in every other living system it is necessary to understand the smallest details of how the components of it work in order to understand the system as a whole. Before we knew about cellular respiration we knew that in order to survive we need to breathe oxygen, but didn't know why or how it is used. Similarly, we know that we behave and we know that electrical potential in our neurons has something to do with it. We need to find out how exactly behavior emerges from potentials, just as we needed to know how oxygen provides us with the ability to continue living. "Life" itself is a product of molecule, atom and ion interaction and to understand all aspects of it we need to consider and closely examine these relationships. Thus, it is worth devoting time, however much is needed, in order to understand electrical potentials in nerve cells and resulting behaviors.

The problem with that argument is that it doesn't give one much guidance on how small one has to get, nor on how much time one should spend on the small. There are always more things one could learn and always smaller things to study. How decide? PG