Static types become less useful as the runtime truth diverges from your static model. For example, different browsers have different APIs. Your code may type ch

Static types become less useful as the runtime truth diverges from your static model. For example, different browsers have different APIs. Your code may type check against your browser today, but that doesn't mean it will work correctly in the browser from yesterday or tomorrow, or in other browsers. Dynamic types let you smooth over these differences. That's an argument for dynamic types, not against static types, and I think languages with both (TypeScript, ObjC) are a sweet spot.