Generally science works on the basis of reductionism. Things are too complicated to understand as a whole, so we break them down into smaller and smaller parts so that we can understand how those work. And then back up and understand how larger and larger pieces work.
Medicine is a good example. The human body is damn complicated. So we break it down into systems, and systems into organs, and organs into tissues, and tissues into cells, and cells into parts, and those parts down to specific lipid membranes and proteins.
So we learn a lot from that. How certain proteins being expressed cause disease or health. How certain tissues screwing up cause disease or health and so on.
Good stuff.
But what we miss is that things are more complicated than the sum of the parts.
That is where holism comes in. Using medicine as an example again, holism requires looking at the body as a whole. And doing that we learn that our immune system isn't just white blood cells as reductionism told us, but that it's bugs in our gut. That our minds have an effect on our immune system. That when we're stressed our whole bodies create peptides that go everywhere which effects our immune system.
Reducitionism vs. holism is just a strategy of breaking things into parts versus looking at collective behavior. One is not better than the other. They're both necessary. They also are applicable to any discipline.
