Can you see the error? Sagan enters this topic with a clear animus against the profit motive and a pre-established belief that industrial civilization is “ravaging the earth.” These are the obvious cultural biases of a late-20th-century modern liberal. So he considers two alternative theories—that we are destroying the planet by cooling it down, or we are destroying the planet by heating it up—and calls for more government funding to figure out which is correct. But his bias prevents him from seriously considering the obvious third option: that our effect on the Earth’s climate is negligible, any heating or cooling is within the normal range of natural variation, and the benefits of industrial civilization far outweigh any negative effects. But if we don’t treat this as an option, much less as an equally likely option, no government funding is likely to be devoted to pursuing that theory.

This is the original sin of the global warming theory: that it was founded in a presumption of guilt against industrial civilization. All of the billions of dollars in government research funding and the entire cultural establishment that has been built up around global warming were founded on the presumption that we already knew the conclusion—we’re “ravaging the planet”—and we’re only interested in evidence that supports that conclusion.

That brings us to where we are today. The establishment’s approach to the scientific debate over global warming is to declare that no such debate exists—and to ruthlessly stamp it out if anyone tries to start one.