Imagine this stark dilemma: you can have either a Princeton education without a diploma, or a Princeton diploma without an education. Which gets you further on the job market? For a human capital purist, the answer is obvious: four years of training are vastly preferable to a page of paper. But try saying that with a straight face. Sensible versions of the signaling model don’t imply the diploma is clearly preferable; after all, Princeton teaches some useful skills. But you need signaling to explain why choosing between an education and a diploma is a head-scratcher rather than a no-brainer.
