Normally, in the political sphere, the business meeting or on the Internet, there is nothing like a good debate to flush out the issues and get people thinking more deeply about their views. It helps us make up our mind on subjects we might not know a lot about.

Debate has its limitations, however. Some people are better than others at performing it. Irrespective of the merits or strengths of the arguments, good debaters will make themselves appear sympathetic to the audience. They will use pathos and evoke emotion. They will use humour and make use of clever soundbites where possible. There is an element of conjuring in the best debaters: little rhetorical tricks that we in the audience may not be aware of, but can do wonders to get people onside.

There is also a sense that the best ideas from each side can lead to a better position overall. Seeking a middle ground is a viable position for a disinterested viewer to take. The argument can be made that if both views are being represented, then they are somehow equal, and that there are important points to be gained from both sides.

When it comes to scientific issues, public debates don’t work quite so well. First of all, no matter how good a debater you are, it has no effect on the underlying science. A skilled creationist debater can argue until the cows come home that God created the Universe in 6 days. He can use every rhetorical device and trick in the book to persuade his audience, but it doesn’t make evolution and a 4.5 billion year old Earth any less true. So too with gravity,  or any number of well established scientific theories. These theories were not developed in the courtroom, or by TV debates, or by pressure groups, or forums on the Internet. There was no appeal to the public to decide their veracity. They came about in the lab, through field work, experimentation, data analysis and published papers. Sure, there would have been debates – many of them – but these debates are technical and professional ones, focused on the quality of the evidence and the methods used. Such arguments rarely play well in front of a TV audience.

Secondly, once scientific theories are established, there is no middle ground. Just as 1 plus 1 is always 2, that too is usually the case in science. Reality works in particular ways. Gravity, electromagnetism, nuclear physics and biochemistry all operate on strict physical laws that don’t change just because someone doesn’t like them. A good thing it is too, as our computers, the cars we travel on, and the boilers for our hot water would not work if it were not the case.

You can’t just come along and equate your opinion or belief, no matter how deeply held, with a well established scientific principle, unless you have serious evidence to back it up. There is no sense that creationism is partly true. No sense that the successive dilutions advocated by homeopathy are of any practical use. Why? Because their advocates have not brought any useful evidence to the table, properly supporting their beliefs, while at the same time accounting for everything else that the existing scientific theories tell us. To take the middle ground in such cases, you are comparing apples, not with other apples, but with a copy of a facsimile of what once used to be an orange but now could be a giraffe, or anything you are having yourself. A scientific theory can only be modified or upended by better scientific evidence, not by a change in public opinion.

Equating pseudo-scientific opinion with well established science is known as “false balance”. It’s widely practiced in the media, where the he-said / she-said debating format is in wide use. A frequent outcome is that a casual listener can come away believing in nonsense, merely because the rhetoric on the nonsensical side of the argument was more persuasive than the expert view.

False balance is everywhere. Creationists in America have tried every trick in the book to inject their particular brand of stupidity into the US education system. There have been incessant efforts to put alternative medicine on a par with actual medicine, despite a long-standing failure to establish scientific plausibility, or to prove their modalities work better than placebo. Climate change deniers are active in the public sphere, using techniques borrowed from creationists and tobacco companies to cast doubt on the research. In Ireland, anti-fluoridation groups are seeking to change public health policy, despite numerous research studies giving fluoridation a green light at low dosages. All of these groups use public debate and public pressure as proxies instead of proper scientific research – because the science does not support their position.

Many prominent scientists are reluctant to engage in debates of this nature because it gives the other side a recognition that they don’t deserve, and offers the possibility of losing a debate because their rhetorical skill might not be as good as the other person’s. These are genuine concerns, however it’s a problem because public pressure and public debate can, and does, move the needle. It is possible for laws to be changed despite the best efforts of scientists. Legislators are rarely scientifically educated themselves. Simply avoiding debate gives all kinds of pressure groups a carte blanche to force through the most wrong-headed legislation possible.

I am minded of Christopher Hitchens, who never shirked any debates, even when his opponent’s points were extreme, terrifyingly offensive and in no sense based on reality. He recognised that how we learn things is based on science, but how we move forward is by public debate. We need both the sense of discovery and the ability to persuade. We need good communicators who can counter the propagandists from the other side while making a forceful case for science in public policy.

The following video is an oldie but a goodie. Dara O’Briain outlines the problem of false balance better than I ever could.