Are low-skilled workers made better or worse off as a result of the $9 minimum wage? It's almost a no-brainer to conclude that being hired at $5 an hour puts more food on the table than not being hired at $9. What's more, minimum wages reduce training opportunities. Most of us gain skills through on-the-job-training. Minimum wage laws deny that opportunity.
A more insidious effect of minimum wages, as racists everywhere know, is that it lowers discrimination costs. Say a white and a black were equally productive and an employer prefers white workers to black workers. Since he has to pay $9 an hour no matter whom he hires, the cost of discriminating against the black worker is zero. But if it were legal for the black worker to offer a lower price, there'd be a cost to discrimination. That's precisely why South African whites demanded that blacks be paid the minimum wages -- they wanted to cheapen discrimination costs.
Gephardt's speech is to be commended for its public service, namely that of revealing the underlying motive for minimum wages: making sure that one class of workers doesn't have to compete with another.