The NAACP has called on blacks to avoid traveling on American Airlines because it has a tendency to mistreat black passengers.

The boycott can be an effective weapon, so when we agree with the goal, we should support it.

It's not an all-or-nothing thing. Cutting out most of your purchases from a company is almost as good as ceasing totally.

The second article seems to endorse one erroneous assumption: that if several competing companies are equally bad, you must treat them equally. This is like saying that if several armies are attacking you, you must counterattack them all at once.

The boycott is a weapon, not a punishment. The state has an obligation to treat all citizens fairly, because it is so strong. The weak, however, have no obligation to be "fair" to all the strong that mistreat them. On the contrary, they should do whatever is most effective. Often that means to pick one target at a time and boycott it until it makes a substantial concession. Then target another one.