Downward causation

Downward causation is a way of thinking about how the small parts of something can have an effect on the bigger parts of the same thing. It's like if you wanted to make a picture using lots of colored pieces of paper. Each piece of paper is a small part of the picture, but when you put them all together, the small parts created the bigger picture. Downward causation is kind of like that, but instead of putting pieces of paper together, you're looking at how small pieces, like the cells in your body, can make a big difference in the big things it's part of, like your whole body.