You have probably heard the story of the scorpion that convinces a frog to carry it across a river. Halfway across, the scorpion stings the frog, which means both will drown. The frog does not understand; the scorpion explains, "I couldn't help myself. It's my nature."

In the abstract, worker-owned enterprises and labor unions would appear to have much in common. Both share the goal of improving pay and working conditions. Both aim to give workers a say in the workplace. And both belong on any progressive's short list of strategies for building a more just economic system.

But when unions and worker-owned businesses actually interact, they sometimes act more like the fabled arachnid.