Why study economics?

As a follow-up to my last post on values and humility in economics, I thought the following video (which Mankiw shared on his blog) of Steve Marglin talking about heterodox economics is great:

Marglin gives two reasons to study mainstream economics in his talk. One of them resonates strongly with me because it is part of why I'm studying economics right now; it is the language of power. While I'm more interested in morbidity and mortality than I am in interest rates, much of health policy, aid policy, and development policy is done by -- or strongly influenced by -- those who speak the language of economics. For the other reason Marglin gives (and of course, there are many others) you'll have to watch the talk (it's good).