"I will never shop at Walmart as they support child labor and environmental degegration and so forth."

Such kind of sayings are pretty trendy these days, particularly by those of the middle income and upper income brackets who are somewhat politically active. It's easy to make such a political statement, but does it actually have much of an impact? Probably not.

It's great to have personal virtues and to make good choices for what you want to support. You might be a vegetarian or you might avoid big box stores all together. That is a personal choice and not a public choice. You alone abstaining from a certain pattern of consumption will not stop it or modify it.

Boycotts do work. But not at the individual level.

If you get a large mass of people together, and you all agree not to shop at a store or engage in a pratice you have the possibility of making an impact—particularly if the goal is pragmatic and able to be done at a level that equals the boycott.

Nobody is going to make major concessions to a few people. Many places will make minor concessions to organized activists who give pragmatic alternatives to the current. Many plces will make major concessions if there is enough public support for a change, pragmatic or not.

Boycotts are symbolic. Yet, they can inspire minor or major changes based on the public support for the boycotts. They also can create awareness and make governments act in response. Lawmakers are often more willing to consider a group's issues then the company most directly effected by the proposal.