Merits of Theory

Hal Varian has a nice article on What Use is Economic Theory?
Varian views Economics as Policy Science and then gives a number of reasons why economic theory is helpful in this regard:

1. Theory as a substitute for data
2. Theory helps keep track of benefits and costs
3. Theory helps relate seemingly disparate problems
4. Theory can generate useful insights
5. A theory that is wrong can still yield insight
6. Theory provides a method for solving problems
7. Theory is an antidote to introspection
8. Verifying that something is obvious may show that it isn’t
9. Theory allows for quantification and calculation
10. Economics is amenable to experimental verification