Developing expertise carries costs of its own. We can become experts in some areas, like speaking a language or knowing our favorite foods, simply by living our lives, but in many other domains expertise requires considerable training and effort. What’s more, expertise is domain specific. The expertise that we work hard to acquire in one domain will carry over only imperfectly to related ones, and not at all to unrelated ones. In the end, as much as we may want to become experts on everything in our lives, there simply isn’t enough time to do so. Even in areas where we could, it won’t necessarily be worth the effort. It’s clear that we should concentrate our own expertise on those domains of choice that are most common and/or important to our lives, and those we actively enjoy learning about and choosing from.