Here’s a riddle for you: Say a 747 airplane is sitting on a treadmill the size of a normal runway. As the airplane accelerates north, the treadmill precisely matches its acceleration in the other direction (if you were standing on it, you would move south). The 747 needs to move forwards (north) at about 290kmh in order to generate enough lift to take off. According to the rules above, if the airplane reaches that speed the treadmill must be moving 290kmh backwards (south).

Can the airplane take off in these circumstances? Will it move forward, despite the backwards movement of the treadmill? Or will it simple stay perfectly stationary due to the opposing force?

It’s a great little physics puzzle in and of itself, but what I really find fascinating about it is the absolute disaster of a conversation is produces. After a few minutes puzzling, people will proclaim their answer turn in surprise when anyone disagrees with them, and then spend the next couple of hours getting incredibly angry as they try to explain to the morons around them why they are wrong. This puzzle is so incredibly divisive that not only were Mythbusters and the fabulous webcomic XKCD prompted to address it, but the definitive proof they both produced (the plane does indeed take off) was still debated all over the internet on a variety of technicalities, conceptual confusions and just outright denial.

How on earth did a simple physics puzzle, with literally zero consequence for anyone involved, manage to stir up such a Shakespearean level of fury on both sides? Well not to put too fine a point on it, the people who were right were arseholes.

Rather than clearly explain why the plane would take off (the wheels basically make the movement of the treadmill irrelevant – they’re not what’s supplying the forward thrust, so they just spin twice as fast) they generally reacted to opposition with disbelief, condescending explanations of basic physics, and more often than not, by just calling opponents stupid. Those who thought the plane would stay still (myself included) reacted more or less in kind, as the stationary plane idea was intuitively powerful (since we’re more used to thinking of how cars work than planes, and a car would stay still since the thrust comes through the wheels themselves).

All in all the entire thing spiralled into absolute chaos as more reasonable voices were overwhelmed and recruited by the crazy ones, the scent of blood attracted trolls, and no one got around to genuinely asking the question why the other side disagreed (as opposed to something along the lines of “How are you possibly failing to grasp this?” or “How are you able to type and breath at the same time?” for example).

This mess could have been (and in my case, was) corrected by explaining the correct answer in terms that catered for what the other side needed. Of course the second the first angry barb was posted, the odds of that happening became virtually zero (this is the internet after all), but the point stands and it highlights a very important ethical concept: The distinction between the Principle and the Practical.

Often ethics deals purely with the Principle of a matter. What is right and what is wrong? What is the correct course of action? Is Marriage a good thing or a bad thing and on what basis? Determining the Principle of a matter is critically important, and definitely the biggest part of ethics – coming up with a rock-solid answer for something like Abortion is a great way to get your arse handed to you if you can’t back it up all the way down to the foundations.

But what far too many philosophers and ethicists fails to acknowledge (or wilfully ignore) is that a Principle that doesn’t acknowledge and account for Practical factors is completely goddamn useless.

For example: Eating meat causes suffering for a marginal human benefit. Alternatives exist that provide sufficient nutrition, without the suffering caused by meat production. Therefore, in Principle, eating meat is unethical.

This conclusion is completely, undeniably correct. And alone, it is absolutely useless. So what if eating meat is unethical? You reckon just pointing that out is going to have the slightest influence on most people, let along the colossal and very profitable industry that has been built around our desire to eat meat? People enjoy the taste, and more importantly, they are used to having it available. Ask the average person to choose between what they are used to and an ethical principle they prefer wasn’t true, and you’re going to get ignored a lot. Push the point and they will actively oppose you in defence.

The same is true of virtually any debate, especially highly controversial ones; fail to acknowledge, accept and account for the Practicalities of the issue and you’re in for a bad time. It may well be blindingly obvious that coal mining must cease in the face of catastrophic climate change, but unless we acknowledge the economic impact this will have on mining towns and are able to offer them alternatives, they will resist the message by any means they can.

Need a better illustration? Look no further than Richard Dawkins, the incredibly aggressive missionary of atheism. Mr Dawkins’ is a scientist and he does the profession proud – his assertions are always founded in solid evidence and backed up by sound evidence. He has won thousands of adherants across the world over to atheism and locked horns with every religious institution he could get his hands on. He is, in Principle, completely correct. In Practice however, the man is a total disaster. To call Richard Dawkins an arsehole is being too nice. He’s rude, he’s belligerent and he’s strayed in racism on occasion. While Dawkins has won thousands to the cause of atheism, he has arguably set its cause back years by drawing a line in the sand with his violent rhetoric, forcing people to choose a side, then ridiculing anyone who disagrees with him. By denying the Practical reality that religion, right or wrong, is an incredibly integral part of many peoples’ identities, cultural norms and value systems, Dawkins has irrevocably lost every religious moderate who might otherwise have considered atheism, agnosticism, or just been happy with secularity.

But the distinction between Principle and Practical doesn’t just apply to big political issues – it’s relevant to virtually every disagreement you will ever have. It may well be your partner’s turn to do the dishes, but if you fail to acknowledge and account for the practical reality that they had a hard day at work, you’re setting yourself up for a fight. Your colleague most definitely shouldn’t smoke due to the health effects on themselves and those around them, but fail to account for the fact that they are chemically addicted and you’re not going to get anywhere.

I know that this distinction makes it sound like we all have to cater for the idiots of the world, and in some cases that’s true (at least you’ll make some progress, if at the expense of your pride) but for the most part this distinction serves as a good reminder that most people we disagree with are not stupid at all; they just see the world through a different set of facts. Telling them they’re seeing things wrong is not enough – you need to offer them a better vision that they can believe in to win them over.