The article below, published in 2012, complements the new article "The fuel for conspiracy theories is the decomposition of capitalism" which looks at the proliferation of conspiracy theories about the origin or role of the Covid-19 crisis. It is striking how in the intervening period, the acceleration of capitalist decomposition, and particularly the rise of populist parties and governments, has brought these distorted visions into the mainstream. But it remains as necessary as ever for marxists to show why such approaches are a significant barrier to understanding the real workings of this system.