In October 2006, 659 economists signed a public call sponsored by the Economic Policy Institute for a raise in the minimum wage–bringing, one would assume, the professional expertise of their deep understanding of economic science to the table.
Daniel Klein and Stewart Dompe, economists at George Mason University, surveyed a bunch of them to get their reasons for supporting a minimum wage hike, and 95 responded. While part of the authors' deal with the surveyed was that they wouldn't comment on their comments as they were published, I'll point out that many of them have very little to do with economic science per se.** A few examples:
Alan Blinder: ….Regardless of Pareto efficiency, we do not allow indentured servitude or child labor. Similarly, a $7.25 minimum wage would state that society deems it wrong to pay less.
Amitava Dutt: Reducing poverty, reducing inequality. Creating a culture where people realize that some basic needs of people should be satisfied.
Robert Haveman: …giving low wage workers a feeling that they are less marginalized than they now feel.
John R. Morris: Economic justice for low income people.
Jeffrey Waddoups: Reducing wage inequality will increase the quality of democratic institutions.
I was hepped to the study via Tyler Cowen at Marginal Revolution, who has his own longer collection of excerpts from Klein and Dompe's respondents, and he and his commenters have their own thoughts.
**UPDATE: That's because, as the original Marginal Revolution link didn't specify, and as my quick read-through of the study didn't catch either, those responses are specifically to a question that asked them to discuss "broad sociopolitical mechanisms"–thus making the responses openly those of economists speculating beyond economic science. I apologize for my misreading.