What is it to think like a mountain? How is it that many of our decisions go wrong, sometimes producing negative side-effects? You might remember hearing about a hole in the ozone layer that appeared last century. No one intended to create that hole. But we did it. We didn’t intend to put mercury in our brains and lead in our bones. A recent study tested 62 samples of human placenta and found microplastics in every single one of them. How do things go wrong on personal and planetary scales? And how can we do better?