When it comes to climate change,
debating whether it exists is just a polite way of trying to deny that it's an issue. It's actually a pretty effective stutter step, since it accomplishes what most deniers want to achieve: paralysis. Instead of debating what to do about climate change, they're happy to debate whether or not it's real in the first place.
So when the campaign of Michigan's Republican Senate candidate Terri Lynn Land answers a question from The Washington Post's Greg Sargent like this...
Terri believes that there should be a healthy and educated debate on the impact of human activity on our environment
...she's siding with the deniers, because there is no way to have a healthy and educated debate about the existence of something that's a scientific fact.