I recently read a book by a biologist who doesn’t apply the evolutionary theory she no doubt knows well. Barbara Ehrenreich’s Nickel and Dimed: On (Not) Getting By in America is her compelling picture of American workers (especially single moms) trying to make ends meet in minimum wage jobs.

Our empathy with and sympathy for these deserving folks should not blind us to the perverse consequences of good intentions gone awry. Let’s consider raising the minimum wage. Will it help these people? Ms. Ehrenreich thinks so. She’s right...but alas only for a lucky few.

Economist Linda Gorman explains: “Minimum wage laws place additional obstacles in the path of the most unskilled workers...struggling to reach the lowest rungs of the jobs ladder.”

The best path to a good job is any job. Entry-level jobs teach workers the skills and employment etiquette (e.g., showing up on time) they need to move up the job ladder. Why does raising the minimum wage for the lowest skilled reduce the chances of getting this critical training?

Incentives matter. This is a key principle of economics. Consider the owner of a diner. The market determines how much she can charge for her food. It also determines the price she pays for her ingredients (e.g., flour, milk, etc.).

Mandating she pay her workers a wage above the market rate does two things. First: higher wages attract more-skilled applicants for traditionally low-skill jobs such as bussing tables. Research at Michigan State University found that “increases in the minimum wage raise the probability that more-skilled teenagers leave school and displace lower-skilled workers from their jobs.” Often those displaced are adults transitioning from welfare to work.

Here’s the second effect. Raising the minimum wage increases her labor costs. She will likely respond in a combination of ways. She can pass increased costs to customers with higher prices; she can use cheaper ingredients; or she can substitute capital for labor, e.g., purchase ready-cut fries rather than hire someone to slice potatoes. She faces incentives to lay off workers or hire fewer.

Even activist groups like the Association for Community Organizations for Reform Now (ACORN) that are at the forefront of the living wage movement have faced this reality. In 1996, ACORN’s California offices filed suit to exempt the organization from the state’s minimum wage laws -- at the time, just $4.25/hour. In court papers they wrote, “California’s minimum-wage laws...affect the quality and quantity of staff which Plaintiff can retain.... [T]he more that ACORN must pay each individual outreach worker...the fewer outreach workers it will be able to hire.”

“Progressives” who argue that raising the minimum wage does not increase unemployment need to answer this question: If raising the minimum wage to $6.65 from $5.15 an hour has no harmful effect on employment, why not make it $12.50? OK, then $25.00. Why not mandate a middle-class life for all?

Raising the minimum wage has another highly pernicious effect -- it lowers the cost of discrimination. Higher wages attract more applicants than employers want to hire. With so many people to chose from, an employer faces little cost for exercising her prejudices.

What’s behind the “progressive” campaign for increasing the minimum? It’s not an accident that labor unions are among the most active supporters. Here’s why.

Unskilled nonunion workers can compete with skilled union workers only by offering their services for less. Increasing the minimum wage reduces this competition. When unions advocate higher minimum wages, they make the labor market less competitive, and can demand higher wages for their members.

Barbara Ehrenreich’s mistake is to assume the people she met are permanently trapped in dead-end experiences. In fact, American society is characterized by a high degree of income mobility. A 1995 report from the Federal Reserve Bank of Dallas showed that almost three-fourths of those in the bottom quintile of income in 1975 moved up by 1991. Those who are poor today will not necessarily be poor tomorrow.

Over time, success depends on an individual’s character -- integrity, intelligence, and a strong work ethic -- and education. Today’s minimum wage jobs allow low-skilled workers to build their human capital and their reputations. Both are keys to a better future.