Tyler Cowen discusses: opportunity cost. When you make a decision, do you weigh all of the costs? Do you consider the tradeoffs you’re making? If so, you are assessing the opportunity cost. To borrow an example from history, Cowen asks whether the Great Wall of China was a good or bad idea. It was intended to keep China safe from invasion and certainly there were benefits. But it required a lot of labor (as many as 800,000 people working on it!) and was extremely expensive to build. There were benefits but also very significant tradeoffs. Examples of tradeoffs and opportunity cost are all around us.