Do you buy organic apples because you think they taste better or because you're trying to buy redemption for your own participation in a pernicious capitalist system? In this lecture, compellingly illustrated by the RSA Animate crew, the philosopher Slavoj Zizek criticizes charity and what he calls "cultural capitalism"—think TOMS shoes or Fair Trade coffee—as palliatives that only perpetuate an immoral economic system.
Zizek's views actually aren't that radical. His point isn't that socially or environmentally enlightened buying habits aren't good. He's just arguing that there's an "element of hypocrisy" involved because those acts also support the economic structures that cause environmental and social problems in the first place.
As far as I can tell, Zizek would prefer you to buy Fair Trade coffee as long as you recognize it isn't the ultimate solution to the injustices suffered by coffee growers.