A few years ago, I had an argument with a friend who didn't give his children any vaccinations. I promised not to talk about vaccines with him again. I broke that vow when Covid 19 arrived. We ran out of new colors for our replies after we duked it out in email threads. He said something that caught me off guard. In the past year, we argued more than we had in the previous decade. He said he didn't know about you but he loved it.

He wasn't the only one. The cognitive cage fights were something I looked forward to. We were closer together because of arguing. We both opened up. We admitted that we were wrong on some things.

A productive disagreement is uncommon in our world. According to research, the average person is more likely to talk to a stranger who shares their political views than a friend who doesn't. That isn't a good thing. I have studied how to build our argument literacy for years. It is a skill that is influenced by your mindset. A good debate is about both people making discoveries.

Too many of us think like prosecutors and politicians when we disagree. You are attempting to proselytise your views. You are attacking someone else's. You don't listen to people unless they share your views.

Illustration of a man raising his hands

Illustration: Hannah Robinson/The Guardian

I usually get prosecutor mode when I hear someone talk like a preacher. Ignorance is the most offensive thing that offends me. It is my professional responsibility as a social scientist and as a human being to correct you if I think you are incorrect. I have been referred to as a logic bully. It took me a long time to realize that hammering people with facts doesn't always win the argument. You have already concluded that you are correct and they are wrong. You have turned a switch that stops you from thinking critically.

In a pair of clever experiments run by an international team of cognitive scientists, people had to generate logical arguments on a variety of issues, then evaluate other people's answers to the same questions. The participants didn't know that one of their own arguments had been included in the set they were being asked to evaluate When they thought that argument was made by someone else, more than half of them rejected it.

Our reasoning is not very well thought out. We have our own opinions about standards. If you weren't the one selling it, you might not buy the case at all.

The harder it is to keep control of your critical thinking skills, the more charged the issue is. Many liberals were angry when the Supreme Court overturned the case. I watched as their reasoning began to fall apart. Many argued that it was wrong to walk away from precedent, forgetting that they stood against precedent when they tried to overturn the 1972 ruling that banned gay marriage. Conservatives fall into the same trap. They insisted that regulations to inject a vaccine into their body were a violation of their constitutional freedom.

If two people always agree, at least one of them is failing to think critically

We want bulletproof facts before we will rethink our convictions. Confirmation bias is only one of the reasons for the tendency to seize ideas that affirm our views. It is also because of distances. We tend to be too close to our own arguments to evaluate them. We need other people to hold up a mirror. Friction can be useful. One of them is failing to think critically or speak candidly if they agree. It is possible to learn from a difference of opinion. The people who teach you the most are the people who don't know what they're talking about.

A friend of mine works in healthcare. He said he could help me identify flaws in my reasoning. He pointed out that I was telling a story when I saidVaccines are safe. What's the safest thing to do? What is the effectiveness? The man was correct. I had fallen prey to a type of bias. When we take a complex spectrum and make it into two different categories. We need to look for the shades of grey if we want to have a better argument.

Photograph of someone throwing a glass of wine at someone else over dinner

‘Great minds don’t think alike – they challenge each other to think again.’ This image and top: food and prop styling: Liam Baker. Manicurist: Mara Soares at Beautii using OPI. Hand models: Emily Hayden and Joelle Dyson. Photograph: Jay Brooks/The Guardian

In the Difficult Conversations Lab at Columbia University, psychologists asked people on opposite sides of the abortion debate to have a 20-minute discussion and then write a joint statement. They read an article about guns before the meeting. The odds of finding common ground on abortion were boosted by an easy edit to the article. In the first version, the gun issue was seen as a war between two camps, and in the second version, it was seen as a complex issue that could be seen through many different perspectives. Conservatives and liberals both supported universal background checks for gun ownership. People came to the abortion discussion with a more open mind after seeing the shades of grey on guns.

It was necessary for me to bring that complexity into my argument. I asked my friend how he would rate the benefits of vaccines. We were able to agree on the standards. The severity of adverse effects from vaccines would have to be weighed against the severity of Covid-19. He said my view was biased when I showed him the evidence. I should be questioning the status quo instead of arguing one-sidedly. The goal isn't to challenge a narrative, it's to find the truth

If you want to have a good argument, it's important to talk about how you argue. We should discuss how to assess the facts before we debate them. Balanced arguments give more weight to the strongest evidence. He wanted to debunk the results of multiple randomized controlled trials by showing a correlation between vaccination rates and mortality. He said that adverse events could be suppressed by big pharma and that the results of the trials could be exaggerated.

For an exclusive behind-the-scenes look at the magazine's biggest features, as well as acurated list of our weekly highlights, sign up for our Inside Saturday newsletter.

My friend helped me understand why I didn't think logically. I was able to help him find a hole in his car. I wanted to know if he thought the Earth was round. He agreed. I asked him to think about what it would look like if he looked at evidence in the same way he does vaccines. Physicists are paid to lie and astronauts are paid to lie. He may want to see it with his own eyes. I asked a second question. It isn't an optical illusion if he can see a round Earth from space. You can see that the Earth is spinning, but you can hear it standing still. I shared some of his concerns about vaccines. He is more in the Flat Earther camp than the science camp. He said for the first time that he understood what you were saying.

People who don't believe in scientific evidence don't deny it all the time. Each time they board a plane, climate change deniers believe in physics. Whenever a vaccine sceptic takes an antibiotic, they show their trust in medicine.

The harder it is to recognize your biases the stronger your convictions are. It is possible to find an issue where views are less extreme. I didn't have to attack my friend's conclusions, I just had to help him reflect on his own thoughts. He wanted us to switch sides on the debate. He sent me a study that showed that people who were unvaccinated had a higher risk of contracting Covid and dying from it than people who were vaccine-boosted.

The highest compliment from someone who disagrees with you is not ‘You were right.’ It’s ‘You made me think.’

Illustration of a woman holding out her hands in frustration

Illustration: Hannah Robinson/The Guardian

Someone who disagrees with you isn't the one to give the highest compliment. You made me ponder. When we used to see simplicity, good arguments helped us recognize complexity. The purpose of debate is not to agree on anything. Critical thinking is promoted.

It wasn't polite to disagree as a child. We shy away from disagreements with our partners when we are grown ups. We never prepare for the big ones. It's like learning to balance on a tightrope You wouldn't walk across the canyon in the morning. You would use a rope and a safety net to get to the top. If you only argue when the stakes are high, you can't think or learn. It's important to train for small fights. Try not to clash on tax policy.

The vaccine debate has been going on for two years. We don't see eye to eye on a lot of things He told me that the official reports for Covid-19 deaths were based on flawed data and that we don't know how many deaths were actually caused by the outbreak. I told him that the researchers tracked total excess all-cause, which is the difference between actual death rates in 185 countries and the expected number of deaths if there had not been a swine flu epidemic. It appears that vaccines saved almost 20 million lives. He is waiting for the long-term data.

words of advice about the art of persuasion in speech bubbles

There are 6 ways to win an argument.

We have been teaching each other a lot. He has educated me about the number of people that need to be treated in order for one person to benefit from a Covid vaccine.

They challenge each other to think again. Intellectual chemistry doesn't mean you agree with someone. Your disagreements with them are enjoyable. The arrangement of sounds is called harmony. Music can be made with creative tension.