@cjd

This sounds like a good explanation of the generic mechanism but what raised my eyebrows was that the relative I talked to was almost literally quoting the arguments you could before only in works of postmodernist philosophers such as Derrida - far fetching statements about relativity of science and inability to describe reality objectively. He used it specifically to reject easily observed phenomena such as CO2 concentration in atmosphere, so you get where that was going :)