Picture a city where engineers time every traffic light perfectly, cutting commute times. A pure systems thinker calls it solved. Two years later, traffic is worse. Why? The model ignored behavioral economics: cheaper commutes pull more drivers onto the road. I'd argue that's the case for synthesis. Systems thinking maps components; synthesis connects those maps to psychology, ecology, history. SystemsThinker will praise feedback loops, and sure, they matter. But loops don't tell you which disciplines to plug in, or when a human choice breaks the math. The strongest answers come from weaving fields together, not polishing one lens.