Alan Blinder: I would not put large weight on this, but I think that to some extent attitudes and mores matter. 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.
Peter Dorman: Since Tocqueville (at least) there is a well-established argument that greater equality of income and respect is associated with better democratic performance. This is a near-consensus position in political theory.
Arindrajit Dube: Increased income (and reduced inequality) has broad effects throughout society and polity; this includes (but is not limited to) increased self worth, increased ability to use added time to spend with kids, attend community college, etc., from an income effect.
Amitava Dutt: Reducing poverty, reducing inequality. Creating a culture where people realize that some basic needs of people should be satisfied.
Robert M. Feinberg: I’m not sure if this is exactly what is meant here, but I would see notions of fairness playing a role.
John R. Morris: Economic justice for low income people.
Jesse Rothstein: I believe that a great deal of bargaining happens within parameters that are determined, in part, by societal expectations. Government policy has some role in determining those expectations.
Paul Swaim: …I think it is important that adults working full time can earn enough to make a substantial contribution to supporting a decent living standard and take pride in their status as workers. Put differently, people playing by the rules should not feel like total losers (or be considered as such by their fellow citizens). The minimum wage can probably make a modest contribution to approaching this objective.
William Van Lear: Suggests a society committed to fairness and recognizes that power has a role in determining outcomes.
Mark Votruba: Vast disparities in wealth and income stability of democratic capitalism, as suggested by Alan Greenspan. I would add that our sense of community is undermined, which in turn undermines the social norms towards “appropriate” social behaviors, especially by those at the bottom.
Jeffrey Waddoups: Reducing wage inequality will increase the quality of democratic institutions.
Bernard Wasow: A low cost demonstration of concern for low wage workers that causes little damage. Elicits a buy-in by low wage workers to the polity
Henry W. Zaretsky: Improved living conditions for affected workers and their families. Less likely to become dependent on public programs such as welfare and Medicaid. More incentive to seek work. More stake in the system. More independence.
It is easy to read these and think "Ah, how narrow is neoclassical economics in contrast to these fine thoughts." My response is instead: "These people are making a mountain out of a molehill." Bernard Wasow is the guy who makes the most sense.
If you wish to understand the gap between market-oriented and more left-wing economists, this piece is an excellent place to start.