I recently listened to an episode on Econ talk. They were talking about the value of economists' advises in policy making. Obviously, economists are not physicists largely because the phenomenon economists dealing with is overwhelmingly " high causal density". As we can see from the many issues that economists cannot agree upon, the study of economy involves many personal opinions. As a matter of fact, economists may never able to quantify something. We might be able to know the direction the economy can move if something happens, but it is just too difficult for anyone to quantify the magnitude of the movement in confidence. Therefore, I am in sympathy of the role economists play. For those who are interested, you can take a look at this episode from econtalk.
Manzi on Knowledge, Policy, and Uncontrolled | EconTalk | Library of Economics and Liberty