He means a vicious cycle, which is technically a positive feedback loop: The worse things get, the more they get worse. Negative feedback means when the system

He means a vicious cycle, which is technically a positive feedback loop: The worse things get, the more they get worse. Negative feedback means when the system is working properly, an unexpected perturbation will cause the system to correct itself automatically. But since the general public thinks of positive as good and negative as bad, he's using the word "negative" to describe a bad situation. This kind of thing bugs me because I know control theory, but it's really in the same category as "Is Program X an X11 client or an X11 server?"