The title that I chose for this page is indicative of one of the key questions of environmental communication: what information can be trusted? In theory, data is just a piece of information; a length, a volume, a mass. In the practice of environmental communication it becomes an argument in support of a cause. And if, as I suggest, the environmental debate is indeed polarized, data is the equivalent to ammunition in a fight or war. Data can be manipulated, misrepresented, concealed and even invented. Personally, I am most interested in the effect of the collective unconscious (or our common cultural inheritance) on the reliability of environmental information. Is it a lie when the collector of the data isn’t aware of her own bias? And why is data so ineffective in changing people’s minds?