The Illusion of Balance problem has another facet: The notion that there are two sides to every issue and that both sides are equally valid. This is usually manifest in the news by interviewing people of “both” sides of a given issue and giving them equal time and weight. Doing so implies that both sides are just as valid as the other. This is not necessarily the case.
This illusion of balance stems from the fact that most of our political and social debates do have two sides, if only by fiat. (It often seems like there might be more than two sides, doesn’t it? But we have a two-party system and two sides generally seems to make for a tidier debate in any case.) Fair enough. If we’re discussing, say, immigration reform, getting a Democrat and a Republican to discuss their parties’ views on the issue is just good reporting.
The problem is that sometimes there really aren’t two sides (or, rather, the two sides aren’t equally valid). If, for example, an astronomer was being interviewed and the shape of the Earth came up, you’d be appalled if the media interviewed a flat-earther for a contrary view. It’d be daft. The shape of the Earth isn’t really in doubt and even giving equal time (and thus,implicitly, equal weight) to the counter-argument is a best bad practice and worst dishonest.
So that was an extreme example, but this comes up all the time in less extreme cases. Consider the perpetual “debate” the country seems to have over teaching evolution. There’s little scientific debate about whether species evolve in time; the evidence for that is much too compelling for anything short of extraordinary counter-evidence to reopen that issue. And yet the news media hardly ever seems to interview a biologist without getting someone from the Discovery Institute or some other group that’s not interested in the science. The same is true with Anthropogenic Global Warming, the connection between tobacco and lung cancer, etc.
What do all of these have in common? They’re questions of science. While a lot of scientific issues are unsettled and honesty requires talking to both sides. (Take the issue of how much water might have been on Mars at some point in the past. It’s not a settled issue and a good story on this would interview several people with different views.) But listen to the scientists involved: if the actual researchers are overwhelmingly saying the same thing, then odds are any “debate” you see is manufactured. This is doubly true if some other group has something to gain by there being a debate at all. (In the case of Evolution, the Creationists have made it clear that they want Christianity taught in public schools. In the case of Global Warming… well, you know who has an interest in not admitting that the science there is pretty much decided.)